Process for producing benzoxazine derivative and production intermediate thereof

ABSTRACT

Processes for producing antibacterial agents and intermediates useful in producing antibacterial agents are provided and include producing compound (VI-a) in accordance with the following reaction schema, as well as production intermediates thereof

This is a divisional of application Ser. No. 10/922,832 filed Aug. 23,2004 now U.S. Pat. No. 7,087,778, which is a divisional of applicationSer. No. 10/070,556 filed Jun. 21, 2002, now U.S. Pat. No. 6,872,823,which is a 371 of PCT Application No. PCT/JP00/06094 filed Sep. 7, 2000.The entire disclosures of the prior applications, application Ser. Nos.10/922,832, 10/070,556, and PCT/JP00/06094, are hereby incorporated byreference.

TECHNICAL FIELD

The present invention relates to intermediates which are useful inproducing antibacterial compounds and processes for producing the same.

BACKGROUND ART

(3S)-(−)9-fluoro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylicacid (levoflaxacin, LVFX: JP-A-62-252790, the term “JP-A” as used hereinmeans an “unexamined published Japanese patent application.)

is known as an excellent synthetic antibacterial agent.

As intermediates in the production of this levofloxacin, compoundsrepresented by formula (VI-a) (hereinafter referred to as compounds(VI-a); the same will apply to compounds represented by other formulae)are also useful:

(wherein X¹ and X², each independently represents a halogen atom).

As intermediates for racemic9-fluoro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylicacid (oflxacin, OFLX):

compounds represented by formula (VI):

(wherein X¹ and X², each independently represents a halogen atom; and R⁵and R⁶, each independently represents an alkyl group) are useful.

Conventional processes for producing the compound (VI-a) are as follows.

The production process reported by Japanese Patent No. 2,612,327 shownin the above figure suffers from a problem that epimerization arisesunder basic or acidic conditions and thus the yield of optically active(R)-NPNB is lowered.

In the process reported by Japanese Patent No. 2,771,871 which is amicrobial reduction method, it is troublesome to purify the productsince the physical properties of the product are not so largelydifferent from those of the starting material.

Further, the process reported by Japanese Patent No. 2,573,269 leavesmuch to be improved as an industrial process, since an expensiveasymmetric acyloxyboron alkali metal hydride is used therein as areducing agent.

In the optical resolution method reported by JP-B-7-20946 (the term“JP-B” as used herein means an “examined Japanese patent publication),furthermore, it is needed to explore the reuse of the unnecessary isomerwhich is formed theoretically at a ratio of 50%.

The production process reported by U.S. Pat. No. 5,644,056 relates to areaction of a racemate. To produce levofloxacin by this process,therefore, it is required to optically resolve the obtained product andthe unnecessary isomer should be racemized or inverted. In addition, thespecification of this patent discloses no experimental example ofoptically active compound.

The process reported by the Chinese document (Chinese Chemical LettersVol. 6, No. 10, 857–860 (1995)) suffers from a problem that anadditional step is needed for the deprotection of thep-toluenesulfonyloxy group used as a protective group.

DISCLOSURE OF THE INVENTION

The present invention relates to processes by which the compound (VI-a)important as intermediate in the production of levofloxacin can beeconomically synthesized within a short period and which are thusindustrially favorable production process. As a result of intensivestudies, the present inventors have found out that the object can beachieved by producing an intermediate of levofloxacin in accordance withthe following synthesis pathways, thus completing the present invention.The following figure shows the processes according to the presentinvention for producing the compound (VI) from the compound (I).

Accordingly, the present invention provides processes for industriallyadvantageously producing compound represented by the formula (VI-a)which is an intermediate for industrially advantageously producinglevofloxacin:

Namely, the present invention relates the following processes.

Process A:

A process which comprises reacting a compound represented by formula(I):

with a compound represented by formula (II-1-a) in the presence of abase:

to give a compound represented by formula (III-1-a):

reducing this compound into a compound represented by formula (IV-a):

reacting this compound with a compound represented by the followingformula:

to give a compound represented by formula (V-a):

and then treating this compound in the presence of a base.Process B:

A process which comprises reacting a compound represented by formula(I):

with a compound represented by formula (II-2-a) in the presence of abase:

to give a compound represented by formula (III-2-a):

eliminating the hydroxyl-protective group (the substituent R⁴) of thiscompound to give a compound represented by formula (IV-a):

reacting this compound with a compound represented by the followingformula:

to give a compound represented by formula (V-a):

and then treating this compound in the presence of a base.Process C:

A process which compreses reacting a compound represented by formula(I):

with a compound represented by formula (II-1-a) in the presence of abase:

to give a compound represented by formula (III-1-a):

reducing this compound into a compound represented by formula (IV-a):

treating this compound in the presence of a base to give a compoundrepresented by formula (VII-a):

and reacting this compound with a compound represented by the followingformula:

Process D:

A process which comprises reacting a compound represented by formula(I):

with a compound represented by formula (II-2-a) in the presence of abase:

to give a compound represented by formula (III-2-a):

eliminating the hydroxyl-protective group (the substituent R⁴) of thiscompound to give a compound represented by formula (IV-a):

treating this compound in the presence of a base to give a compoundrepresented by formula (VII-a):

and then reacting this compound with a compound represented by thefollowing formula:

Process E:

A process which comprises reacting a compound represented by the formula(I):

with a compound represented by formula (II-1) in the presence of a base:

to give a compound represented by formula (III-1):

and then subjecting this compound to the following Method 1 or 2;Method 1:

in case of the compound represented by the formula (III-1) where R³ isnot a hydrogen atom, a method which comprises treating this compoundwith an enzyme capable of asymmetrically hydrolyzing an ester or aliquid culture medium of a microorganism, cells of this microorganism orprocessed cells of this microorganism and, after the completion of thistreatment, isolating the product from the treated liquid mixture;

Method 2:

in case of the compound represented by the formula (III-1) where R³ is ahydrogen atom, a method which comprises optically resolving thiscompound by reacting with an optically active organic base;

to obtain a carboxylic acid compound represented by the followingformula:

esterifying this compound in the presence of an alcohol represented bythe following formula:R⁷—OHto give an ester compound represented by the following formula:

reducing this compound into a compound represented by formula (IV-a):

reacting this compound with a compound represented by the followingformula:

to give a compound represented by formula (V-a):

and then treating this compound in the presence of a base.Process F:

A process which comprises reacting a compound represented by formula(I):

with a compound represented by formula (II-1) in the presence of a base:

to give a compound represented by formula (III-1):

and then subjecting this compound to the following Method 1 or 2;Method 1:

in case of the compound represented by the formula (III-1) where R³ isnot a hydrogen atom, a method which comprises treating this compoundwith an enzyme capable of asymmetrically hydrolyzing an ester or aliquid culture medium of a microorganism, cells of this microorganism orprocessed cells of this microorganism and, after the completion of thistreatment, isolating the product from the treated liquid mixture;

Method 2:

in case of the compound represented by the formula (III-1) where R³ is ahydrogen atom, a method which comprises optically resolving thiscompound by reacting with an optically active organic base;

to obtain a carboxylic acid compound represented by the followingformula:

esterifying this compound in the presence of an alcohol represented bythe following formula:R⁷—OHto give an ester compound represented by the following formula:

reducing this compound into a compound represented by formula (IV-a):

treating this compound in the presence of a base to give a compoundrepresented by formula (VII-a):

and then reacting this compound with a compound represented by thefollowing formula:

Process G:

A process which comprises reacting a compound represented by thefollowing formula:

or by the following formula:

with a compound represented by the following formula in the presence ofa metal catalyst under a hydrogen gas atmosphere, optionally in thepresence of a dehydrating agent or an acid:CH₃COCOOR³to give a compound represented by formula (III-1):

and then subjecting this compound to the following Method 1 or 2;Method 1:

in case of the compound represented by the formula (III-1) where R³ isnot a hydrogen atom, a method which comprises treating this compoundwith an enzyme capable of asymmetrically hydrolyzing an ester or aliquid culture medium of a microorganism, cells of this microorganism orprocessed cells of this microorganism and, after the completion of thistreatment, isolating the product from the treated liquid mixture;

Method 2:

in case of the compound represented by the formula (III-1) where R³ is ahydrogen atom, a method which comprises optically resolving thiscompound by reacting with an optically active organic base;

to obtain a carboxylic acid compound represented by the followingformula:

esterifying this compound in the presence of an alcohol represented bythe following formula:R⁷—OHto give an ester compound represented by the following formula:

reducing the compound into a compound represented by formula (IV-a):

reacting this compound with a compound represented by the followingformula:

to give a compound represented by formula (V-a):

and then treating this compound in the presence of a base.Process H:

A process which comprises reacting a compound represented by thefollowing formula:

or by the following formula:

with a compound represented by the following formula in the presence ofa metal catalyst under a hydrogen gas atmosphere, optionally in thepresence of a dehydrating agent or an acid:CH₃COCOOR³to give a compound represented by formula (III-1):

and then subjecting this compound to the following Method 1 or 2;Method 1:

in case of the compound represented by the formula (III-1) where R³ isnot a hydrogen atom, a method which comprises treating this compoundwith an enzyme capable of asymmetrically hydrolyzing an ester or aliquid culture medium of a microorganism, cells of this microorganism orprocessed cells of this microorganism and, after the completion of thistreatment, isolating the product from the treated liquid mixture;

Method 2:

in case of the compound represented by the formula (III-1) where R³ is ahydrogen atom, a method which comprises optically resolving thiscompound by reacting with an optically active organic base;

to obtain a carboxylic acid compound represented by the followingformula:

esterifying this compound in the presence of an alcohol represented bythe following formula:R⁷—OHto give an ester compound represented by the following formula:

reducing the compound into a compound represented by formula (IV-a):

treating this compound in the presence of a base to give a compoundrepresented by formula (VII-a):

and then reacting this compound with a compound represented by thefollowing formula:

Process I:

A process which comprises reacting a compound represented by thefollowing formula:

with a compound represented by the following formula:CH₃COCOOR³to give a compound represented by the following formula:

asymmetrically reducing this compound into a compound represented byformula (III-1-a):

reducing this compound into a compound represented by formula (IV-a):

reacting this compound with a compound represented by the followingformula:

to give a compound represented by formula (V-a):

and then treating this compound in the presence of a base.Process J:

A process which comprises reacting a compound represented by thefollowing formula:

with a compound represented by the following formula:CH₃COCOOR³to give a compound represented by the following formula:

asymmetrically reducing this compound into a compound represented byformula (III-1-a):

reducing this compound into a compound represented by formula (IV-a):

treating this compound in the presence of a base to give a compoundrepresented by formula (VII-a):

and then reacting this compound with a compound represented by thefollowing formula:

[in each of the above formulae, X¹, X² and X³, each independentlyrepresents a halogen atom; R¹ represents a leaving group; R³ representsa hydrogen atom or a carboxyl-protective group; R⁴ represents ahydroxyl-protective group; R⁵ and R⁶, each independently represents analkyl group having 1 to 6 carbon atoms; R⁷ represents acarboxyl-protective group; and Y represents an alkoxy group having 1 to6 carbon atoms, a halogen atom or a dialkylamino group (wherein thealkyl groups may be the same or different and each represents an alkylgroup having 1 to 6 carbon atoms); and substituents which will be usedhereinafter respectively have the same meanings as defined above].

The present invention further relates to the following processesconstituting each of the Processes as described above.

Concerning the processes for producing the compound represented by theformula (III-a) in Processes G and H;

a process for producing a compound represented by the formula (III-1):

which is characterized by reacting a compound represented by formula(I-0):

(wherein Z represents a nitro group or an amino group; and other groupsare those as defined above;)with a compound represented by the following formula;CH₃COCOOR³optionally in the presence of an acid acceptor or an acid, in thepresence of a metal catalyst under a hydrogen gas atmosphere;

the above process for producing a compound represented by the formula(III-1) wherein R³ is a hydrogen atom;

the above process for producing a compound represented by the formula(III-1) wherein R³ is a methyl group;

the above process for producing a compound represented by the formula(III-1) wherein R³ is an ethyl group;

the above process for producing a compound represented by the formula(III-1) wherein Z is an amino group;

the above process for producing a compound represented by the formula(III-1) wherein Z is a nitro group;

the above process for producing a compound represented by the formula(III-1) wherein Z is an amino group and R³ is a hydrogen atom;

the above process for producing a compound represented by the formula(III-1) wherein Z is an amino group and R³ is a methyl group;

the above process for producing a compound represented by the formula(III-1) wherein Z is an amino group and R³ is an ethyl group;

the above process for producing a compound represented by the formula(III-1) wherein Z is a nitro group and R³ is a hydrogen atom;

the above process for producing a compound represented by the formula(III-1) wherein Z is a nitro group and R³ is a methyl group; and

the above process for producing a compound represented by the formula(III-1) wherein Z is a nitro group and R³ is an ethyl group.

Concerning the processes involving the separation of a single opticalisomer in Processes E, F, G and H;

a process for producing a carboxylic acid compound represented by thefollowing formula:

which is characterized by treating an ester compound among the compoundsrepresented by formula (III-1):

with an enzyme capable of asymmetrically hydrolyzing an ester or aliquid culture medium of a microorganism, cells of this microorganism orprocessed cells of this microorganism and then isolating the productfrom the treated liquid mixture;

a process for producing a carboxylic acid compound represented by thefollowing formula:

which is characterized by treating an ester compound among the compoundsrepresented by formula (III-1):

with an enzyme capable of asymmetrically hydrolyzing an ester or aliquid culture medium of a microorganism, cells of this microorganism orprocessed cells of this microorganism and then removing a compoundrepresented by formula (III-1-b) from the treated liquid mixture;

a process for producing an ester compound among the compoundsrepresented by formula (III-1-a):

which is characterized by treating an ester compound among the compoundsrepresented by formula (III-1):

with an enzyme capable of asymmetrically hydrolyzing an ester or aliquid culture medium of a microorganism, cells of this microorganism orprocessed cells of this microorganism and then isolating the productfrom the treated liquid mixture;

a process for producing an ester compound among the compoundsrepresented by the formula (III-1-a):

which is characterized by treating an ester compound among the compoundsrepresented by formula (III-1):

with an enzyme capable of asymmetrically hydrolyzing an ester or aliquid culture medium of a microorganism, cells of this microorganism orprocessed cells of this microorganism and then removing a carboxylicacid compound represented by the following formula from the treatedliquid mixture;

each of the above-described production processes wherein R³ is a methylgroup;

each of the above-described production processes wherein R³ is an ethylgroup;

each of the above-described production processes wherein the enzyme tobe used in the treatment is esterase, protease or chymotrypsin;

each of the above-described production processes wherein themicroorganism is a microorganism selected from among bacteria belongingto the genera Bacillus, Micrococcus and Actinomyces;

each of the above-described production processes wherein themicroorganism is a microorganism selected from among fungi belonging tothe genera Aspergillus, Rhizopus, Nannizia and Penicillium; and

each of the above-described production processes wherein themicroorganism is a microorganism selected from among yeasts belonging tothe genera Candida, Saccharomyces and Zygoascus.

Concerning the processes involving the separation of a single opticalisomer in Processes E, F, G and H;

a process for producing a 2-(2,3,4-trihalogenoanilino)propionic acidcomposed of a single optical isomer, which is characterized by opticallyresolving a compound represented by the following formula:

by using an optically active organic base;

a process for producing a 2-(2,3,4-trihalogenoanilino)propionic acidcomposed of a single optical isomer, which is characterized by treatinga compound represented by the following formula:

with an optically active organic base to give a diastereomeric salt ofone of the optical isomers of 2-(2,3,4-trihalogenoanilino)propionic acidand the optically active organic base and then treating thisdiastereomeric salt with an acid;

the above-described processes for producing a single optical isomerwherein the optically active organic base is a compound represented bythe following formula:

(wherein Aryl represents an aryl group optionally having a halogen atom,a nitro group, a cyano group, a carbamoyl group, an alkyl group having 1to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms; and

R⁸, R⁹ and R¹⁰, each independently represents:

(1) a phenyl group optionally having a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, a halogenoalkyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, acarbamoyl group or a cyano group;

(2) a benzyl group optionally having a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, a halogenoalkyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, acarbamoyl group or a cyano group;

(3) an alkyl group having 1 to 6 carbon atoms; or

(4) a hydrogen atom);

the above-described processes for producing a single optical isomerwherein the optically active organic base is 1-phenylethylamine;

-   -   the above-described processes for producing a single optical        isomer wherein the optically active organic base is        1-(p-tolyl)ethylamine; and    -   the above-described processes for producing a single optical        isomer wherein the optically active organic base is        1-phenyl-2-(tolyl)ethylamine.

Concerning the production processes involving the separation of a singleoptical isomer in Processes E, F, G and H;

a process for producing an ester compound represented by the followingformula:

which is characterized by treating a carboxylic acid compoundrepresented by the following formula:

in the presence of a compound represented by the following formula:R⁷—OHand an acid catalyst; and

a process for producing an ester compound represented by the followingformula:

which is characterized by treating a carboxylic acid compoundrepresented by the following formula:

in the presence of a compound represented by the following formula:R⁷—OHand an acid catalyst.

Concerning the production processes involving the separation of a singleoptical isomer in Processes E, F, G and H;

a process for producing an ester compound in a racemate represented byformula (III-1):

which is characterized by treating an ester compound among the compoundsrepresented by formula (III-1-b):

in the presence of a base;

a process for producing an ester compound as described above wherein thebase is a nitrogen-containing heterocyclic compound;

a process for producing an ester compound as described above wherein thebase is 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or1,8-diazabicyclo[4.3.0]undec-5-ene (DBN);

a process for producing an ester compound as described above wherein thebase is an alkali metal or alkaline earth metal carbonate; and

a process for producing an ester compound as described above wherein thebase is potassium carbonate.

Concerning the production processes involving the separation of a singleoptical isomer in Processes E, F, G and H;

a process for producing a racemic carboxylic acid compound representedby the following formula:

which is characterized by racemizing an ester compounds among thecompounds represented by the following formula (III-1-b) by treating inthe presence of a base:

and then hydrolyzing;

a process for producing a racemic carboxylic acid compound as describedabove wherein the base is a metal alkoxide;

a process for producing a racemic carboxylic acid compound as describedabove wherein the base is potassium tertiary butoxide;

a process for producing a racemic carboxylic acid compound as describedabove wherein the base is an alkali metal or alkaline earth metalcarbonate;

a process for producing a racemic carboxylic acid compound as describedabove wherein the base is potassium carbonate.

Concerning the processes for producing the compound (V-a) in ProcessesA, B, E, G and I;

a process for producing a compound represented by tformula (V-a):

which is characterized by reacting a compound represented by formula(IV-a):

with a compound represented by the following formula under basicconditions:

Concerning the processes for producing the compound (VI-a) in ProcessesA, B, E, G and I;

a process for producing a compound represented by formula (VI-a):

which is characterized by reacting a compound represented by the formula(V-a):

under basic conditions;

a process for producing a compound represented by the formula (VI-a) asdescribed above wherein the basic conditions are basic conditions withthe coexistence of a base and a phase transfer catalyst;

a process for producing a compound represented by the formula (VI-a) asdescribed above wherein the base is an alkali metal hydroxide or analkaline earth metal hydroxide;

a process for producing a compound represented by the formula (VI-a) asdescribed above wherein the base is potassium hydroxide;

a process for producing a compound represented by the formula (VI-a) asdescribed above wherein the phase transfer catalyst is a quaternaryammonium salt or a crown ether;

a process for producing a compound represented by the formula (VI-a) asdescribed above wherein the phase transfer catalyst is a quaternaryammonium salt;

a process for producing a compound represented by the formula (VI-a) asdescribed above wherein quaternary ammonium salt istetra(normal-hexyl)ammonium chloride, trimethylbenzylammonium chloride,triethylbenzylammonium chloride, trimethylphenylammonium chloride ortetrabutylammonium hydrogen sulfate.

Concerning the steps of reducing an ester compound in Processes A, C, E,F, G, H, I and J;

a process for producing a compound represented by formula (IV-a):

which is characterized by treating a compound represented by formula(III-1-a):

or a compound represented by the following formula:

in an aprotic solvent with a metal borohydride compound and an alcohol;

a process for producing a compound represented by the formula (IV-a) asdescribed above wherein the compound represented by the formula(III-1-a) is an ester compound;

a process for producing a compound represented by the formula (IV-a) asdescribed above wherein R³ and R⁷ are each an alkyl group having 1 to 6carbon atoms;

a process for producing a compound represented by the formula (IV-a) asdescribed above wherein R³ and R⁷ are each a methyl group;

a process for producing a compound represented by the formula (IV-a) asdescribed above wherein R³ and R⁷ are each an ethyl group;

each process for producing a compound represented by the formula (IV-a)as described above wherein the aprotic solvent is a solvent selectedfrom the compounds of the group consisting of aromatic hydrocarbons,alkanes, cycloalkanes, ethers, halogenated hydrocarbons and acetic acidesters;

each process for producing a compound represented by the formula (IV-a)as described above wherein the aprotic solvent is an aromatichydrocarbon;

each process for producing a compound represented by the formula (IV-a)as described above wherein the aprotic solvent is an alkane;

each process for producing a compound represented by the formula (IV-a)as described above wherein the aprotic solvent is a cycloalkalne;

each process for producing a compound represented by the formula (IV-a)as described above wherein the aprotic solvent is an ether;

each process for producing a compound represented by the formula (IV-a)as described above wherein the aprotic solvent is a halogenatedhydrocarbon;

each process for producing a compound represented by the formula (IV-a)as described above wherein the aprotic solvent is an acetic acid ester;

each process for producing a compound represented by the formula (IV-a)as described above wherein the alcohol is a primary alcohol;

each process for producing a compound represented by the formula (IV-a)as described above wherein primary alcohol is methanol;

each process for producing a compound represented by the formula (IV-a)as described above wherein the metal borohydride compound is sodiumborohydride; and

each process for producing a compound represented by the formula (IV-a)as described above wherein X¹, X² and X³ are each a fluorine atom.

Concerning the steps of reducing an ester compound in Processes A, B, E,G and I;

a process for producing a compound represented by formula (VI-a):

which is characterized by reacting a compound represented by formula(III-1-a):

or a compound represented by the following formula:

with a metal borohydride compound in an aprotic solvent in the presenceof an alcohol to give a compound represented by formula (IV-a):

then reacting this compound with a compound represented by the followingformula under basic conditions:

to give a compound represented by formula (V-a):

and treating this compound under basic conditions.

Moreover, the present invention relates to the following compoundsconcerning the above Processes and steps.

Compounds represented by formula (III-1):

(wherein X¹, X² and X³, each independently represents a halogen atom;and R³ represents a hydrogen atom or a carboxyl-protective group);

compounds represented by formula (III-1-a):

(wherein X¹, X² and X³, each independently represents a halogen atom;and R³ represents a hydrogen atom or a carboxyl-protective group);

compounds represented by formula (III-1-b):

(wherein X¹, X² and X³, each independently represents a halogen atom;and R³ represents a hydrogen atom or an alkyl group);

each of the compounds of the formula (III-1), (III-1-a) or (III-1-b)wherein R³ is a hydrogen atom;

each of the compounds of the formula (III-1), (III-1-a) or (III-1-b)wherein R³ is a methyl group;

each of the compounds of the formula (III-1), (III-1-a) or (III-1-b)wherein R³ is an ethyl group;

compounds represented by formula (V):

compounds represented by formula (V-a):

each of the compounds of the formula (III-1), (III-1-a), (III-1-b), (V)or (V-a) wherein X¹, X² and X³ are each a fluorine atom;

salts of carboxylic acid compounds represented by the following formula:

with an optically active organic base;

salts of compounds represented by the following formula:

with an optically active organic base;

the above-described salts wherein the optically active organic base is acompound represented by the following formula:

(wherein Aryl represents an aryl group optionally having a halogen atom,a nitro group, a cyano group, a carbamoyl group, an alkyl group having 1to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms; and

R⁸, R⁹ and R¹⁰, each independently represents:

(1) a phenyl group optionally having a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, a halogenoalkyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, acarbamoyl group or a cyano group;

(2) a benzyl group optionally having a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, a halogenoalkyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, acarbamoyl group or a cyano group;

(3) an alkyl group having 1 to 6 carbon atoms; or

(4) a hydrogen atom);

the above-described salts wherein the optically active organic base is1-phenylethylamine;

the above-described salts wherein the 1-phenylethylamine is(R)-(+)-1-phenyethylamine;

the above-described salts wherein the optically active organic base is1-(p-tolyl)ethylamine;

the above-described salts wherein the 1-(p-tolyl)ethylamine is(R)-(+)-1-(p-tolyl)ethylamine;

the above-described salts wherein the optically active organic base is1-phenyl-2-(p-tolyl)ethylamine;

the above-described salts wherein the 1-phenyl-2-(p-tolyl) ethylamine is(S)-(+)-1-phenyl-2-(p-tolyl) ethylamine;

each of the above-described salts wherein X¹, X² and X³ are each afluorine atom.

The present invention furthermore relates to a process for producing thecompound (levofloxacin) represented by the following formula:

with the use of a compound represented by the formula (VI-a) which hasbeen produced by each of the processes and each of the compounds asdescribed above, which is characterized by involving the following stepsof preparing a compound represented by formula (VI-a) by any ofProcesses A to J:

treating this compound with a boron trifluoride compound to therebyconvert it into a boron chelate compound represented by the followingformula:

reacting this compound with 4-methylpiperazine to give a compoundrepresented by the following formula:

and then cleaving off the boron chelate of this compound.

The present invention furthermore relates to the following productionprocesses:

a process for producing levofloxacin as described above wherein ProcessA is used as the process for producing the compound represented by theformula (VI-a);

a process for producing levofloxacin as described above wherein ProcessB is used as the process for producing the compound represented by theformula (VI-a);

a process for producing levofloxacin as described above wherein ProcessC is used as the process for producing the compound represented by theformula (VI-a);

a process for producing levofloxacin as described above wherein ProcessD is used as the process for producing the compound represented by theformula (VI-a);

a process for producing levofloxacin as described above wherein ProcessE is used as the process for producing the compound represented by theformula (VI-a);

a process for producing levofloxacin as described above wherein ProcessF is used as the process for producing the compound represented by theformula (VI-a);

a process for producing levofloxacin as described above wherein ProcessG is used as the process for producing the compound represented by theformula (VI-a);

a process for producing levofloxacin as described above wherein ProcessH is used as the process for producing the compound represented by theformula (VI-a);

a process for producing levofloxacin as described above wherein ProcessI is used as the process for producing the compound represented by theformula (VI-a);

a process for producing levofloxacin as described above wherein ProcessJ is used as the process for producing the compound represented by theformula (VI-a);

a process for producing levofloxacin as described above wherein X¹ andX² are each a fluorine atom;

a process for producing levofloxacin as described above wherein theboron trifluoride compound is a boron trifluoride compound composed ofboron trifluoride and an ether compound;

a process for producing levofloxacin as described above wherein theboron trifluoride compound is boron trifluoride diethyl ether complex orboron trifluoride tetrahydrofuran complex;

a process for producing levofloxacin as described above wherein thereaction with 4-methylpiperazine is a reaction carried out in thepresence of a trialkylamine;

a process for producing levofloxacin as described above wherein thetrialkylamine is triethylamine or tributylamine; etc.

Now, the present invention will be illustrated in greater detail. First,substituents used in the present description will be described.

X¹, X² and X³, each independently represents a halogen atom, preferablya fluorine atom.

R¹ represents a leaving group. As the leaving group, halogen atoms,optionally substituted alkylsulfonyloxy groups, optionally substitutedarylsulfonyloxy groups, etc. can be cited.

Examples of the optionally substituted alkylsulfonyloxy groups,methanesulfonyloxy group, ethanesulfonyloxy group, propanesulfonyloxygroup, butanesulfonyloxy group, isobutanesulfonyloxy group,t-butanesulfonyloxy group and trifluoromethanesulfonyloxy group can becited.

Examples of the optionally substituted arylsulfonyloxy groups,benzenesulfonyloxy group, p-toluenesulfonyloxy group,m-toluenesulfonyloxy group, p-nitrobenzenesulfonyloxy group,m-nitrobenzenesulfonyloxy group, p-methoxybenzenesulfonyloxy group,p-chlorobenzenesulfonyloxy group, m-chlorobenzenesulfonyloxy group,2,4-dimethylbenzenesulfonyloxy group and 3,5-dinitrobenzenesulfonyloxygroup can be cited.

As the leaving group, substituted sulfonyloxy groups and halogen atomsare preferable and trifluoromethanesulfonyloxy group, methanesulfonyloxygroup, p-toluenesulfonyloxy group, chlorine atom, etc. are stillpreferable.

R¹ represents —COOR³ or —CH₂OR⁴.

R³ represents a hydrogen atom or a carboxyl-protective group.

The carboxyl-group may be those ordinarily used in the art. Particularexamples thereof include aralkyl groups, alkyl groups, etc.

The term aralkyl groups means groups composed of an alkyl group having 1to 6 carbon atoms and an aryl group. Particular examples thereof includebenzyl group, naphthyl methyl group, etc. The alkyl group may be alinear, branched or cyclic alkyl group having 1 to 6 carbon atoms.Particular examples thereof include methyl group, ethyl group, propylgroup, cyclobutyl group, cyclopentyl group, cyclohexyl group, etc.

As R³, alkyl groups having 1 to 6 carbon atoms are preferable and methylgroup, ethyl group and isopropyl group are particularly preferable.

R⁴ represents a hydroxyl-protective group. As the hydroxyl-protectivegroup, optionally substituted alkyl groups, optionally substituted arylgroups, optionally substituted aralkyl groups, optionally substitutedacyl groups, etc. can be cited.

As the optionally substituted alkyl groups, methoxymethyl group,methoxyethyl group, etc. can be cited.

As the optionally substituted aryl groups, phenyl group, dimethoxyphenylgroup, p-methoxyphenyl group, etc. can be cited.

As the optionally substituted aralkyl groups, α-phenylethyl group,benzyl group, trityl group, tolyl group, etc. can be cited.

As the optionally substituted acyl groups, acetyl group, methoxyacetylgroup, trifluoroacetyl group, chloroacetyl group, pivaloyl group, formylgroup, benzoyl group, p-methoxybenzyl group, p-nitrobenzoyl group, etc.can be cited.

As R⁴, optionally substituted acyl groups are preferable andp-nitrobenzoyl group is particularly preferable.

R⁵ and R⁶ independently represent an alkyl group and methyl group andethyl group are preferable therefor.

R⁷ represents a carboxyl-protective group which may be the same as thegroups cited above concerning R³.

Y represents an alkoxy group, a halogen atom or a dialkylamino group(wherein the alkyl groups may be either the same or different (stillpreferably the same) and each has 1 to 6 carbon atoms). Among all,alkoxy groups are preferable. The alkoxy groups may be alkyl groupshaving 1 to 6 carbon atoms and methoxy group and ethoxy group arepreferable therefor.

In the above reaction scheme, a process for producing one of the isomersis exclusively presented. However, the other isomer can be similarlysynthesized by using the compound having the oposed configuration tocompound (II-a). By using the racemic compound (II), it is also possibleto obtain the compound (VI) in the form of a racemate.

Now, each step of the present invention will be illustrated in detail.

Step from Compound (I) to Compound (III)

The compound (III) can be obtained by reacting the compound (I) with thecompound (II) in the presence of a base. This reaction is carried outusually in a solvent.

The compound (II) occurs as either the compound (II-1) or the compound(II-2) depending on the definition of the substituent R². In thecompound (II), an optically active compound is useful in the productionof LVFX. More particularly speaking, one of the isomers, i.e., thecompound (II-a) is needed in the production of LVFX. The same applies tothe compound (II-1) and the compound (II-2). That is to say, thecompound (II-1-a) and the compound (II-2-a) are needed in the productionof LVFX. These compounds are represented by the following formulae:

The compound (II) can be produced by various methods. It can be obtainedby converting a lactic acid ester compound.

For example, the compound (II-1-a) may be obtained by converting thehydroxyl group in a D-lactic acid ester compound into a group capable ofleaving. That is to say, the hydroxyl group can be converted intoacetoxy group or trifluoroacetoxy group by treating the compound withacetic anhydride or trifluoroacetic anhydride respectively; or into asubstituted sulfonyloxy group such as trifluoromethanesulfonyloxy group,methanesulfonyloxy group or p-toluenesulfonyloxy group by reacting thecompound respectively with trifluoromethanesulfonyl chloride,methanesulfonyl chloride, p-toluenesulfonyl chloride ortrifluoromethanesulfonic anhydride in the presence of a base.

The compound (II-2-a) is obtained by protecting the hydroxyl group ofthe D-lactic acid ester compound, then reducing the carboxyl estermoiety into hydroxymethyl group, protecting the hydroxyl group thusobtained, eliminating the protective group from the hydroxyl grouphaving been preliminarily protected to thereby restore the hydroxylgroup, and then converting it into a leaving group by the same method asdescribed above.

Alternatively, the compound (II-2) can be obtained from 1,2-propanediol.Namely, the terminal hydroxyl group is first protected by using thedifference in the reactivity between the primary and secondary hydroxylgroups. Next, the remaining hydroxyl group is converted into a leavinggroup. In case of using optically active propanediol, the compound(II-2-a) can be obtained.

The compound (III) can be obtained from the compound (I) and thecompound (II). The compound (III-a) is obtained by the reaction with thecompound (II-a); the compound (III-1) is obtained by the reaction withthe compound (II-1); the compound (III-2) is obtained by the reactionwith the compound (II-2); the compound (III-1-a) is obtained by thereaction with the compound (II-1-a); and the compound (III-2-a) isobtained by the reaction with the compound (II-2-a).

The reaction of the compound (I) with the compound (II-1) or thecompound (II-2) can be performed under almost the same conditions. Now,these reactions will be described.

The compound (II) may be used in an amount of 1 to 2 times (by mol),preferably from 1.0 to 1.1 time, as much based on the molar number ofthe compound (I).

As the base, either an inorganic or an organic base may be used.Examples of the inorganic base include alkali metal and alkaline earthmetal carbonates and hydrogencarbonates such as sodium carbonate,potassium carbonate, sodium hydrogencarbonate and potassiumhydrogencarbonate; and alkali metal and alkaline earth metal halidessuch as potassium fluoride, cesium fluoride and potassium iodide.

Examples of the organic base include trialkylamines such astriethylamine and ethyldiisopropylamine; N,N-dialkylaniline derivativeshaving 1 to 4 carbon atoms such as N,N-dimethylaniline andN,N-diethylaniline; and pyridine derivatives optionally substituted byan alkyl group having 1 to 4 carbon atoms such as pyridine and2,6-lutidine.

In case where R¹ is a trifluoromethanesulfonyloxy group, it ispreferable to carry out the reaction in the presence of an organic base,still preferably 2,6-lutidine. In case where R¹ is a halogen atom, amethanesulfonyloxy group or a p-toluenesulfonyloxy group, it ispreferable to carry out the reaction in the presence of an alkali metalor alkaline earth metal carbonate or hydrogencarbonate, still preferablypotassium carbonate.

The base may be used in an amount of from 1 to 3 times (by mol),preferably from 1.1 to 2 times, as much based on the molar number of thecompound (I).

As the solvent, any solvent which exerts no effect on the reaction maybe used. Examples thereof include aromatic hydrocarbon solvents such astoluene and xylene; ether solvents such as diethyl ether,tetrahydrofuran (THF) and 1,4-dioxane; ketone solvents such as acetoneand methyl ethyl ketone; amide solvents such as N,N-dimethylformamide(DMF) and N,N-dimethylacetamide (DMAc); halogenated hydrocarbon solventssuch as dichloromethane and chloroform; ester solvents such as methylacetate and ethyl acetate; and alcohol solvents such as methanol,ethanol and isopropanol (IPA).

In case where R¹ is a trifluoromethanesulfonyloxy group, it ispreferable to use dichloromethane, chloroform, etc. In case where R¹ isa halogen atom, a methanesulfonyloxy group or a p-toluenesulfonyloxygroup, it is preferable to use N,N-dimethylformamide,N,N-dimethylacetamide, toluene, acetone, dichloromethane, etc.

The solvent may be used in an amount of 5 times or more, preferably from10 to 15 times, as much based on the compound (I). (Use of 1 ml of asolvent per gram of the compound (I) is referred to as an amount of 1time).

In case where R¹ is a halogen atom, a methanesulfonyloxy group or ap-toluenesulfonyloxy group, the yield can be elevated by using anadditive. Examples of the additive include phase transfer catalysts,molecular sieves, etc.

Examples of the phase transfer catalysts include quaternary ammoniumsalts such as tetra (normal-hexyl) ammonium chloride andtetra(normal-hexyl)ammonium iodide; and crown ethers such as18-crown-6,15-crown-5.

As the additive, a phase transfer catalyst is preferable. Among all, alipophilic quaternary ammonium salt is still preferable.

The additive may be used in an amount of from 1 to 100%, preferably from5 to 30%, based on the molar number of the compound (I).

In case of reacting the compound (II-1), the reaction temperature is notparticularly restricted so long as it does not exceed the boiling pointof the solvent used. Usually, it ranges from −5° C. to 50° C.,preferably from −5° C. to room temperature. In case of reacting thecompound (II-2), the reaction temperature usually ranges from −78° C. to50° C., preferably from −50° C. to 0° C. and still preferably from −50°C. to −30° C.

Although the reaction time depends on the reaction temperature, thereaction is usually completed within about 30 minutes to 5 days.

In case where the product is the compound (III-1), the product can beused as such in the subsequent step without isolating. That is to say,the steps from the compound (I) to the compound (IV) can be continuouslyperformed.

In the step of producing the compound (IV) from the compound (III), itis needed to select a different method depending on the compound (III),i.e., either the compound (III-1) or the compound (III-2).

The compound (III) can be also produced by the following method.

The compound (III-1) can be obtained by reacting a compound (I-0)

(wherein X¹, X² and X³ each independently represents a halogen atom; andZ represents an amino group or a nitro group); with pyruvic acid (theacid or an ester):CH₃COCOOR³(wherein R³ represents a hydrogen atom or an alkyl group); in a solventin the presence of a metal catalyst under a hydrogen gas atmosphere.

The metal catalyst to be used in this production process is notparticularly restricted, so long as it is usable in a catalytichydrogenation reaction. Among such catalysts, palladium-carbon, Raneynickel and Raney cobalt are preferable.

In this reaction, a dehydrating agent may be added to promote thereaction. The dehydrating agent is not particularly restricted, so longas it exerts no effect on the reaction. For example, use may be made ofanhydrous magnesium sulfate, anhydrous sodium sulfate, a molecularsieve, etc. Among these dehydrating agents, anhydrous magnesium sulfateand anhydrous sodium sulfate are preferable.

The reaction between the compound (I-0) and pyruvic acid can be moreconveniently performed by adding a catalytic amount of an acid andcarrying out the hydrogenation reaction under elevated pressure. Theacid to be added may be either an organic acid or an inorganic acid.Examples thereof include inorganic acids such as hydrochloric acid,nitric acid, sulfuric acid and phosphoric acid; and organic acids suchas substituted carboxylic acid compounds and substituted sulfonic acidcompounds. Examples of the substituted carboxylic acids include aceticacid, trifluoroacetic acid and fumaric acid. Examples of the substitutedsulfinic acid include methanesulfonic acid, trifluoromethanesulfonicacid, benzenesulfonic acid and toluenesulfonic acid. As the inorganicacid to be added, hydrochloric acid and sulfuric acid are preferable.

As the acid to be added, such an acid as described above may be added.Alternatively, it is also possible to select pyruvic acid per se(CH₃COCOOH) as the pyruvic acid derivative used as the reactant, therebymaking the pyruvic acid to serve both as the reactant and the acid forpromoting the reaction.

The acid may be added in a catalytic amount. In case of using an acidother than pyruvic acid, it may be added in an amount of from 1 to 30%(by mol) based on the molar number of the compound (I-0). In case ofusing pyruvic acid per se as a reaction promoter, it may be added in anequimolar amount to the molar number of the compound (I-0). However, aneffect of promoting the reaction can be achieved by further adding it insmall excess. To achieve the catalytic effect, pyruvic acid may be addedin an amount of from about 1 to 5% by mol.

As the solvent, any solvent which exerts no effect on the reaction maybe used without restriction. Examples thereof include alcohol solventssuch as methanol, ethanol, propanol and isopropanol; ether solvents suchas diethyl ether, tetrahydrofuran and 1,4-dioxane; halogenatedhydrocarbon solvents such as dichloromethane and chloroform; amidesolvents such as N,N-dimethylformamide and N,N-dimethylacetamide;dimethyl sulfoxide, acetonitrile, acetone, acetic acid esters, water,etc. It is also possible to use mixtures of these solvents.

Among these solvents, alcohol solvents are preferable and methanol,ethanol and isopropanol are still preferable.

Although the reaction temperature varies depending on the solvent used,it usually ranges from −78° C. to the boiling point of the solvent,preferably from room temperature to the boiling point of the solvent.

The reaction time ranges from 1 to 24 hours. Usually, the reaction iscompleted within 1 to 16 hours.

This process is carried out under a hydrogen gas atmosphere. Thehydrogen gas pressure may usually range form 0.1 to 10 MPa, preferablyfrom 0.1 to 5 Mpa.

In case where this reaction is performed by using a nitrobenzenederivative (Z═NO₂), the nitro group is first reduced into an amino group(an aniline derivative). Then this amino group reacts with the carbonylgroup in pyruvic acid to give an imine compound:

Next, the imino group in this imine compound is hydrogenated into anamino group. (One of the geometric isomers of the imine compound isexclusively presented herein.) It is therefore needless to say that ananiline compound having a reduced nitro group is usable as the startingmaterial in this reaction. This imine compound is obtained either as oneof the geometric isomers or as a mixture of the isomers. Either case isapplicable to the asymmetric reduction.

By the production process of reacting the compound (I-0) with a pyruvicacid compound under reductive conditions, the compound (III-1) isusually obtained as a racemate. To obtain the optically active compound(III-1-a), the imine compound formed by the reaction of the compound(I-0) with the pyruvic acid compound is reduced under asymmetricallyreductive conditions.

The asymmetric reduction reaction of the imine can be achieved by usingthe following reaction conditions:

(1) reduction reactions using boron and an aluminum compound reported inK. Yamada, J. Chem. Soc., Perkin Trans. 1, 265 (1983); S. Ituno, Bull.Chem. Soc. Jpn., 60, 395 (1987); S. Ituno, J. Chem. Soc., Perkin Trans.1, 1859 (1990); B. T. Cho, Tetrahedron Asymmetry, 3, 1583 (1992); T.Sakai, Synlett., 753 (1995); M. Shimizu, Tetrahedron Lett., 36, 8607(1995); C. Bolm, Synlett., 655 (1994); J. M. Brunel, Synlett., 177(1996); R. O. Hutchins, J. Org. Chem., 52, 704 (1987), etc.;

(2) hydrosilylation reactions reported in N. Langlois, TetrahedronLett., 4865 (1973); H. B. Kagan, J. Organomet. Chem., 90, 353 (1975); X.Verdaguer, J. Am. Chem. Soc., 118, 6784 (1996), etc.;

(3) catalytic hydrogenation reactions reported in the followingdocuments and the like (Rh catalyst: A. Levi, J. Chem. Soc., Chem.Commun., 6 (1975); S. Vastag, J. Mol. Catal., 22, 283 (1984); G.-K.Kang, J. Chem. Soc., Chem. Commun., 1466 (1988); W. R. Cullen, J. Mol.Catal., 62, 243 (1990); A. G. Becalski, Inorg. Chem., 30, 5002 (1991);J. Bakos, J. Organomet. Chem., 279, 23 (1985); J. Bakos, J. Organomet.Chem., 370, 263 (1989); J. Bakos, J. Chem. Soc., Chem. Commun., 1684(1991); C. Lensink, Tetrahedron Asymmetry, 3, 235 (1992); C. Lensink,Tetrahedron Asymmetry, 4, 215 (1993); J. M. Buriak, Organometallics, 15,3161 (1996); M. J. Murk, J. Am. Chem. Soc., 114, 6266 (1992); M. J.Burk, Tetrahedron, 50, 4399 (1994); Ir catalyst: F. Spindler, Angew.Chem., Int. Ed. Engl., 29, 558 (1990); A. Togni., Angew. Chem., Int. Ed.Engl., 35, 1475 (1996); T. Morimoto, Chem. Pharm. Bull., 42, 1951(1994); T. Morimoto, Tetrahedron Asymmetry, 6, 2661 (1995); T. Morimoro,Synlett., 748 (1995); K. Tani, Chem. Lett., 955 (1995); K. Satoh,Tetrahedron Asymmetry, 9, 2657 (1998); Y. Ng C. Chan, J. Chem. Soc.,Chem. Commun., 869 (1990); Y. Ng C. Chan, J. Am. Chem. Soc., 112, 9400(1990); R. Sablong, Tetrahedron. Lett., 37, 4937 (1996); Ti catalyst: C.A. Willoughby, J. Am. Chem. Soc., 114, 7562 (1992); C. A. Willoughby, J.Org. Chem., 58, 7627 (1993); C. A. Willoughby, J. Am. Chem. Soc., 116,8952 (1994); C. A. Willoughby, J. Am. Chem. Soc., 116, 11703 (1994); Rucatalyst: C. Botteghi, Chimia, 29, 256 (1975); W. Oppolzer, TetrahedronLett., 31, 4117 (1990); D. E. Fogg, Inorg. Chim. Acta., 222, 85 (1984);and

(4) hydrogen-transfer reduction reactions reported in S. Hashiguchi, J.Am. Chem., Soc., 117, 7562 (1995); A. Fujii, J. Am. Chem. Soc., 118,2521 (1996); N. Uematsu, J. Am. Chem. Soc., 118, 4916 (1996), etc.

In the optically active compounds (III-1-a), a carboxylic acid compound(see the following structural formula):

can be obtained by treating an ester compound of the correspondingcompound with an enzyme capable of asymmetrically hydrolyzing an esteror a liquid culture medium of a microorganism, cells of thismicroorganism or processed cells of this microorganism.

To accomplish asymmetrically hydrolyzing of the ester, the estercompound (racemate) of the compound (III-1) is suspended in anappropriate buffer and then an enzyme capable of asymmetricallyhydrolyzing an ester or a liquid culture medium of a microorganism,cells of this microorganism or processed cells of this microorganism areadded followed by stirring. The enzyme, etc. usable in this reaction isnot particularly restricted, so long as it is capable of asymmetricallyhydrolyzing an ester. Examples of the enzyme include marketed enzymepreparations originating in microorganisms, animals and plants. Forexample, use can be made of various esterases, proteases orchymotrypsins. As the microorganism, use can be made of bacteriabelonging to the genera Bacillus, Micrococcus and Actinomyces; fungibelonging to the genera Aspergillus, Rhizopus, Nannizia and Penicillium;and yeasts belonging to the genera Candida, Saccharomyces and Zygoascus.

By the treatment with the above-described enzyme, microbial cells, etc.,the ester moiety of one of the isomers (enantiomers) of the compound(III-1) is hydrolyzed to give a carboxylic acid. Further, this productis converted into a carboxylic acid salt and thus dissolved in thetreatment liquor. At this point, the treatment liquor is extracted withan organic solvent such as ethyl acetate, chloroform, diisoproyl ether(IPE) or methyl t-butyl ether. Thus, an ester compound (see thefollowing structural formula) which is the unnecessary isomer(enantiomer) of the compound (III-1-b):

can be isolated and collected.

Prior to the extraction of the compound (III-1-b), it is favorable toeliminate the enzyme, microbial cells, etc. by, for example, filtration.After extracting the compound (III-1-b), the treatment liquor isacidified and then extracted with an organic solvent such as diisopropylether, methyl t-butyl ether or ethyl acetate. Thus, a carboxyliccompound of the compound (III-1-a) which is a free compound can beobtained.

The treatment with the enzyme, microbial cells, etc. may be carried outusually at a temperature of from 5° C. to 60° C., preferably from 20° C.to 40° C.

The pH value of this treatment liquor may range from 4 to 9, preferablyfrom 6 to 8.

The treatment with the enzyme, microbial cells, etc. may be carried outfor from 4 hours to 7 days, preferably from 8 hours to 50 hours.

The concentration of the compound (III-1) in the treatment liquorusually ranges from 0.1% to 20% on the weight basis, preferably from0.5% to 5%.

The amount of the enzyme or the liquid culture medium of amicroorganism, cells of this microorganism or processed cells of thismicroorganism is not particularly restricted. In general, it ispreferably used in an amount of from 0.05 to 0.5 times by weight as muchas the compound (III-1) on the dry weight basis.

It is also possible to obtain a carboxylic acid compound of the compound(III-1-b) by using an enzyme or the liquid culture medium of amicroorganism having the reverse asymmetric recognition ability to thecleavage of the ester of the compound (III-1-a) and conversion into acarboxyl group, cells of this microorganism or processed cells of thismicroorganism.

A carboxylic acid compound of the racemic compound (III-1) can beobtained by separating the isomers (enantiomers) by formingdiastereomeric salts with an optically active organic base andcrystallizing them. By further recrystallizing the thus obtained salt byusing an appropriate solvent, a salt having a higher stereoisomericpurity can be obtained.

By treating the thus formed diastereomeric salts with an acid, thecarboxylic compounds of the compound (III-1-a) and the compound(III-1-b) can be separated.

The term “comprises a single (optical) isomer” as used herein means notonly a case in which it is completely free from the other (optical)isomer but also a case in which the other isomer may be present in sucha degree that it does not exert influences upon physical constants.

The term “stereoisomerically pure salt” as used herein has the followingmeaning. In case where an acid and a base constituting a salt havestereoisomers, namely, a salt formed by an acid comprised of a singlestereoisomer and a base similarly comprised of a single stereoisomer isreferred to a stereoisomerically pure salt. That is to say, it means asalt wherein the constituting acid and base are each comprised of asingle stereoisomer. The term “comprises a single stereoisomer” as usedherein may be considered as the state of substantially being free fromother isomer.

Examples of the optically active organic base which can be used informing such salts involve optically active ethylamine derivativesaryl-substituted at the 1-position (1-arylethylamine derivatives)represented by the following formula:

(wherein Aryl represents an aryl group optionally having a halogen atom,a nitro group, a cyano group, a carbamoyl group, an alkyl group having 1to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms; and

R⁸, R⁹ and R¹⁰ each independently represents:

(1) a phenyl group optionally having a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, a halogenoalkyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, acarbamoyl group or a cyano group;

(2) a benzyl group optionally having a halogen atom, an alkyl grouphaving 1 to 6 carbon atoms, a halogenoalkyl group having 1 to 6 carbonatoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, acarbamoyl group or a cyano group;

(3) an alkyl group having 1 to 6 carbon atoms; or

(4) a hydrogen atom).

Examples of the aryl group include phenyl group and naphthyl group. Thearomatic rings of these aryl groups may have one or more substituentssuch as halogen atoms, nitro group, cyano group, carbamoyl group, alkylgroups having 1 to 6 carbon atoms and alkoxy groups having 1 to 6 carbonatoms, or one or more types of these substituents.

As examples of these optically active bases, 1-phenylethylamine,1-(p-tolyl)ethylamine and 1-phenyl-2-(p-tolyl)ethylamine may be cited.

Among these bases, examples of optically active bases capable ofadvantageously forming a salt in combination with the carboxylic acidcompound of the compounds (III-1-a) include (R)-(+)-1-phenylethylamine,(R)-(+)-1-(p-tolyl)ethylamine and(S)-(+)-1-phenyl-2-(p-tolyl)ethylamine.

Examples of optically active bases capable of advantageously forming asalt in combination with the carboxylic acid compound of the compounds(III-1-b) include (S)-(+)-1-phenylethylamine,(S)-(+)-1-(p-tolyl)ethylamine and(R)-(+)-1-phenyl-2-(p-tolyl)ethylamine.

On the other hand, the aromatic rings of the 1-arylethylaminederivatives are not restricted to hydrocarbyl aromatic rings but involvearomatic heterocycles containing sulfur atom, nitrogen atom, oxygen atomand the like. Examples thereof include thiophene, benzothiophene,pyridine, quinoline, isoquinoline, furan, benzofuran, etc.

The optically active base may be used usually in an equimolar amount orless to the molar number of the carboxylic acid compound.

As the solvent for crystallizing or recrystallizing the target salt,various solvents may be used. Examples of solvents usable herein includealiphatic or aromatic hydrocarbon solvents such as n-hexane, n-pentane,benzene, toluene and xylene; alcohol solvents such as methanol, ethanol,propanol, isopropanol, n-butanol and t-butanol; ether solvents such asdiethyl ether, diisopropyl ether, methyl t-butyl ether, tetrahydrofuran,1,2-dimethoxyethane and 1,4-dioxane; amide solvents such asN,N-dimethylformamide and N,N-dimethylacetamide; and halogenatedhydrocarbon solvents such as chloroform, methylene chloride and1,2-dichloroethane (EDC). In addition, use can be also made of water,acetonitrile, acetic acid esters, acetone, etc. Either one of thesesolvents or a mixture of several types thereof may be used.

The solvent may be usually used in an amount of from 1 to 100 times byweight, preferably from about 2 to 50 times by weight.

Although the temperature for the crystallization or recrystallization ofthe desired salt is not definite, temperature conditions usually usedmay be selected. More particularly speaking, it may be performed withina temperature range from ice-cooling to the boiling point of the solventused.

The reaction time usually ranges from 1 to 24 hours.

The carboxylic acid salt may be converted into the free carboxylic acidby treating with an acid. Namely, the carboxylic acid salt is treatedwith an inorganic acid such as hydrochloric acid or sulfuric acidfollowed by isolation by, for example, extraction with an organicsolvent.

Since the isomer (enantiomer) to be used in the production oflevofloxacin is the compound (III-1-a), the other compound (III-1-b) hasno utility value as such. An ester compound of this compound (III-1-b)can be racemized by treating in the presence of a base. Thus, theunnecessary isomer can be converted into the necessary isomer by thismethod.

As the solvent usable in this isomerization reaction, various solventscan be cited. Examples thereof include aliphatic or aromatic hydrocarbonsolvents such as n-hexane, n-pentane, benzene, toluene and xylene;alcohol solvents such as methanol, ethanol, propanol, isopropanol,n-butanol and t-butanol; ether solvents such as diethyl ether,diisopropyl ether, methyl t-butyl ether, tetrahydrofuran,1,2-dimethoxyethane and 1,4-dioxane; amide solvents such asN,N-dimethylformamide and N,N-dimethylacetamide; and halogenatedhydrocarbon solvents such as chloroform, methylene chloride and1,2-dichloroethane. In addition, use can be also made of water,acetonitrile, acetic acid esters, acetone, etc. Either one of thesesolvents or a mixture of several types thereof may be used.

Among these solvents, aromatic hydrocarbons such as toluene and amidessuch as N,N-dimethylformamide and N,N-dimethylacetamide are preferable.

Although the reaction temperature varies depending on the solvent used,it usually ranges from −78° C. to the boiling point of the solvent,preferably from room temperature to the boiling point of the solvent.

The reaction time ranges from 1 to 24 hours, preferably from 1 to 16hours.

The base may be either an organic base or an inorganic base. Forexample, use can be made of hydroxides, carbonates, hydrogencarbonatesand alkoxides of alkali metals and alkaline earth metals such as sodium,potassium, lithium, magnesium and calcium; metal hydrides such as sodiumhydride, potassium hydride and lithium hydride; alkyl lithium reagentssuch as n-butyl lithium, methyl lithium and lithium diisopropylamide;tertiary amines such as triethylamine and N,N-diisopropylethylamine;nitrogen-containing heterocyclic compounds such as1,8-diazabicyclo[5.4.0]undec-7-ene (DBU),1,8-diazabicyclo[4.3.0]non-5-ene (DBN) and N-methylmorpholirie;N,N-dialkylanilines such as dimethylaniline and diethylaniline; etc.

Among these bases, it is preferable to use nitrogen-containingheterocyclic compounds such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU);alkali metal or alkaline earth metal carbonates such as potassiumcarbonate; or alkali metal or alkaline earth metal metal alkoxides suchas potassium tertiary-butoxide (t-BuOK).

The base may be used in an amount of from 0.1 to 15 times by mol,preferably from 1 to 5 times, as much based on the molar number of theester compound of the compound (III-1-b).

To promote the reaction, the reaction may be carried out in the presenceof a quaternary ammonium salt such as tetrabutylammonium bromide orbenzyltriethylammonium chloride; an alkali metal or alkaline earth metaliodide such as potassium iodide or sodium iodide; a crown ether, etc.

The compound (III-1-b) can be converted into a carboxylic acid compoundof the compound (II-1) by racemizing by treating with a base and thenhydrolyzing it.

As the solvent, use can be made of various solvents, for example,aliphatic or aromatic hydrocarbon solvents such as n-hexane, n-pentane,benzene, toluene and xylene; alcohol solvents such as methanol, ethanol,propanol, isopropanol, n-butanol and t-butanol; ether solvents such asdiethyl ether, diisopropyl ether, methyl t-butyl ether, tetrahydrofuran,1,2-dimethoxyethane and 1,4-dioxane; amide solvents such asN,N-dimethylformamide and N,N-dimethylacetamide; and halogenatedhydrocarbon solvents such as chloroform, methylene chloride and1,2-dichloroethane. In addition, use can be also made of water,acetonitrile, acetic acid esters, acetone, etc. Either one of thesesolvents or a mixture of several types thereof may be used.

Among these solvent, aromatic hydrocarbon solvents such as toluene andN,N-dimethylformamide and N,N-dimethylacetamide are preferable.

Although the reaction temperature varies depending on the solvent used,it usually ranges from −78° C. to the boiling point of the solvent,preferably from room temperature to the boiling point of the solvent.

The reaction time ranges from 1 to 24 hours. Usually, the reaction iscompleted within 1 to 16 hours.

The base may be either an organic base or an inorganic base. Forexample, use can be made of hydroxides, carbonates, hydrogencarbonatesand alkoxides of alkali metals and alkaline earth metals such as sodium,potassium, lithium, magnesium and calcium; metal hydrides such as sodiumhydride, potassium hydride and lithium hydride; alkyl lithium reagentssuch as n-butyl lithium, methyl lithium and lithium diisopropylamide;tertiary amines such as triethylamine and N,N-diisopropylethylamine;nitrogen-containing heterocyclic compounds such as1,8-diazabicyclo[5.4.0]undec-7-ene (DBU),1,8-diazabicyclo[4.3.0]non-5-ene (DBN) and N-methylmorpholine;N,N-dialkylanilines such as dimethylaniline and diethylaniline; etc.

Among these bases, it is preferable to use alkali metal alkoxides suchas potassium tertiary-butoxide or alkali metal or alkaline earth metalcarbonates such as potassium carbonate.

The base may be used in an amount of from 0.1 to 15 times by mol,preferably from 1 to 5 times, as much based on the molar number of theester compound of the compound (III-1-b).

To promote the reaction, the reaction may be carried out in the presenceof a quaternary ammonium salt such as tetrabutylammonium bromide orbenzyltriethylammonium chloride; an alkali metal or alkaline earth metaliodide such as potassium iodide or sodium iodide; a crown ether, etc.

The ester is hydrolyzed by using an acid or a base. In the acidichydrolysis, use is made of an acid such as hydrochloric acid or sulfuricacid. In the basic hydrolysis, use is made of a base, for example, analkali metal hydroxide such as sodium hydroxide or potassium hydroxide;an alkali metal carbonate such as sodium carbonate or potassiumcarbonate; or an alkali metal hydrogencarbonate such as sodiumhydrogencarbonate or potassium hydrogencarbonate. The base is usuallyused in the form of an aqueous solution.

The carboxylic acid compound in the compound (III-a), which is obtainedby the hydrolysis with the use of the enzyme, the liquid culture mediumof the microorganism, the microbial cells or the processed microbialcells or the hydrolysis under acidic or basic conditions, can beconverted into an ester compound in a conventional manner. Namely, itmay be reacted with the following alcohol in the presence of an acidcatalyst:R⁷—OH.

Examples of the alcohol usable herein include methanol, ethanol,propanol, isopropanol and n-butanol. By using such an alcohol,esterification toward an ester corresponding to the alcohol proceeds.Although the reaction temperature varies depending on the alcohol used,it usually ranges from −78° C. to the boiling point of the alcohol,preferably from room temperature to the boiling point of the alcohol.Examples of the acid usable herein include hydrochloric acid, sulfuricacid and phosphoric acid. As another esterification method, use can bealso made of the esterification by preparing an acid chloride followedby the treatment with an alcohol.

The carboxylic acid compound among the compounds (III-a) obtained by theasymmetric hydrolysis of the ester or the hydrolysis of the ester in thepresence of an acid or a base can be purified by forming salts withvarious amines. As the amine usable in this purification, it ispreferable to select a highly lipophilic amine and examples thereofinclude cyclic alkylamines such as cyclohexylamine; and aralkylaminessuch as benzylamine and phenethylamine. Among these amines,cyclohexylamine and benzylamine are preferable and cyclohexylamine isstill preferable. A salt of such an amine can be purified byrecrystallization in a conventional manner. As the conditions for thepurification, the conditions for the optical resolution as describedabove can be appropriately used. The amine salt of the carboxylic acidcompound among the compounds (III-1) thus obtained can be converted intoa free compound by treating with an acid. Subsequently, it can beesterified by the above-described method. It is also possible to carryout the esterification while omitting the procedure for obtaining thefree compound by using an acid for the esterification in excess based onthe molar number of the carboxylic acid salt.

Step from Compound (III-1) to Compound (IV)

The compound (IV) can be obtained by reducing the compound (III-1). Thisreaction may be carried out by treating the compound (III-1) in asolvent in the presence of a reducing agent. As the compound (III-1) tobe used in this reduction, one wherein the COOR³ moiety is an ester isparticularly preferable.

Examples of the reducing agent include borohydride reducing agents suchas sodium borohydride, lithium borohydride, calcium borohydride, zincborohydride, magnesium borohydride and sodium cyano borohydride cyanide;and aluminum hydride reducing agents such as lithium aluminum hydride.As the reducing agent, borohydride reducing agents are preferable andsodium borohydride is particularly preferable.

The reducing agent may be used in an amount from 1.1 to 2.5 times bymol, preferably from 1.1 to 1.5 time, as much based on the molar numberof the compound (III-1).

The solvent usable herein is not particularly restricted so long as itexerts no effect on the reaction. Examples thereof include alcoholsolvents such as methanol, ethanol, isopropanol and t-butanol; ethersolvents such as diethyl ether and tetrahydrofuran; etc. As the solvent,alcohol solvents are preferable and isopropanol is still preferable. Incase of using isopropanol, the reaction can be promoted by addingmethanol in an amount from 0.5 to 5 times by mol, preferably from 0.5 to2 times, as much based on the molar number of the compound (III-1).

The reaction temperature may be a temperature exerting no undesirableeffect on the reaction. It preferably ranges from 0 to 60° C., stillpreferably from room temperature to 50° C. The reaction time may rangefrom 1 hour to 20 hours.

As the results of the inventors' examination on this reduction reaction,it is found out that, in case where an optically active compound amongthe compounds of the formula (III-1) is subjected to the reductionreaction, it is favorable to select a non-alcohol solvent (an aproticsolvent) as the solvent and use a metal hydride compound as the reducingagent for the reaction. Namely, it is clarified that in case where thereaction of reducing an optically active compound in this process isperformed in a protic solvent, the steric structure is partly invertedand thus the optical purity is lowered.

As the metal hydride compound, use can be made of a metal borohydridecompound or a metal aluminum hydride compound. Particular examplesthereof include metal borohydride compounds such as sodium borohydride,lithium borohydride, calcium borohydride, potassium borohydride, zincborohydride, magnesium borohydride and sodium cyano borohydride cyanide;and metal aluminum hydride compounds such as lithium aluminum hydride.Among these compounds, metal borohydride compounds are preferable andsodium borohydride is particularly preferable.

The reducing amount may be used in an amount from 1 to 5 times by mol,preferably from about 1.1 to 2 times, as much based on the molar numberof the compound (III-1-a) or (III-1-b).

It this step, it is particularly preferable to use an aprotic solvent.Examples of the aprotic solvent usable herein include linear andbranched aliphatic hydrocarbon solvents such as n-hexane, n-pentane,cyclohexane and cyclopentane; aromatic hydrocarbon solvents such asbenzene, toluene and xylene; ether solvents such as diethyl ether,diisopropyl ether, methyl t-butyl ether, tetrahydrofuran,1,2-dimethoxyethane and 1,4-dioxane; and halogenated hydrocarbonsolvents such as chloroform, methylene chloride and 1,2-dichloroethane.In addition, use can be also made of acetic acid esters, etc. Either oneof these solvents or a mixture of several types thereof may be used.

Among these solvents, aliphatic hydrocarbon solvents such as n-hexaneand cyclohexane, ether solvents such as diisopropyl ether and methylt-butyl ether, and aromatic hydrocarbon solvents such as toluene arepreferable.

As the alcohol added herein, primary alcohols are preferable andmethanol is particularly preferable. The alcohol may be used in anamount of from 3 to 20 times, preferably from about 4 to 15 times, asmuch based on the compound (III-1-a) or (III-1-b).

Although the reaction temperature varies depending on the solvent used,it usually ranges from −78° C. to the boiling point of the solvent,preferably from 10° C. to the boiling point of the solvent.

The reaction time ranges from 1 to 24 hours. Usually, the reaction iscompleted within about 2 to 16 hours.

To perform the reduction reaction in this step without isomerizing theoptically active compound, it is preferable that the compound (III-1-a)or (III-1-b) and the reducing agent are added to the aprotic solvent andthen the alcohol is added thereto (under stirring).

Step from Compound (III-2) to Compound (IV)

The compound (IV) can be obtained by deprotecting the compound (III-2).

Although the deprotection procedure varies depending on the type of R⁴used as the hydroxyl-protective group, it may be carried out by anappropriate method for the type of R⁴ ordinarily used in the art. Incase where R⁴ is an aralkyl group (arylmethyl) or an aralkyloxycabronylgroup, a catalytic hydrogenation reaction may be used. In case where R⁴is an acyl group, a hydrolysis reaction with an acid or an alkali may beused. In case where R⁴ is an alkoxycabronyl group or an ether,decomposition with an acid or treatment with zinc in acetic acid, etc.may be used.

Step from Compound (IV) to Compound (V)

In this step, the compound (V) can be obtained by adding to the compound(IV) a methylenemalonic acid dialkyl ester derivative represented by thefollowing formula:

(wherein R⁵ and R⁶, each independently represents an alkyl group; and Yrepresents an alkoxy group, a halogen atom or a dialkylamino group);followed by heating, or treating the compound (IV) and themethylenemalonic acid dialkyl ester derivative in a solvent in thepresence of a base and a phase transfer catalyst.(1) Method of Adding Methylenemalonic Acid Dialkyl Ester Derivative toCompound (IV)

The methylenemalonic acid dialkyl ester derivative may be used in anamount from 1 to 3 times by mol, preferably from 1.05 to 1.2 time, asmuch based on the molar number of the compound (IV).

The reaction can be performed either without using a solvent or in asolvent. As the solvent, use can be made of any one so long as it exertsno effect on the reaction. Examples thereof include aromatic hydrocarbonsolvents such as toluene and xylene.

It is preferable to perform the reaction without using a solvent orusing an aromatic hydrocarbon solvent such as toluene or xylene.

The reaction temperature is not particularly restricted so long as itdoes not exceed the boiling point of the solvent. It preferably rangesfrom 100° C. to the boiling point of the solvent. Although the reactiontime varies depending on the reaction temperature, it is usuallycompleted within 1 hour to 1 day.

(2) Method of Treating Compound (IV) and Methylenemalonic Acid DialkylEster Derivative in Solvent in the Presence of Base and Phase TransferCatalyst

The methylenemalonic acid dialkyl ester derivative may be used in anamount from 1 to 3 times by mol, preferably from 1.05 to 2 times, asmuch based on the molar number of the compound (IV).

The solvent is not particularly restricted so long as it exerts noundesirable effect on the reaction. Examples thereof include aliphatichydrocarbon solvents such as n-hexane, and n-pentane; aromatichydrocarbon solvents such as benzene, toluene and xylene; ether solventssuch as diethyl ether, diisopropyl ether, methyl t-butyl ether,tetrahydrofuran and 1,4-dioxane; ketone solvents such as acetone andmethyl ethyl ketone; amide solvents such as N,N-dimethylformamide andN,N-dimethylacetamide; halogenated hydrocarbon solvents such asdichloromethane and chloroform; ester solvents such as methyl acetateand ethyl acetate; alcohol solvents such as methanol, ethanol,isopropanol, n-butanol and t-butanol; and halogenated hydrocarbons suchas chloroform, methylene chloride and 1,2-dichloroethane. Among thesesolvents, aromatic hydrocarbon solvents, amide solvents, ketone solventsand halogenated solvents are preferable and toluene,N,N-dimethylformamide, N,N-diemthylacetamide, acetone anddichloromethane are still preferable. Among these solvents, amidesolvents such as N,N-dimethylformamide and N,N-dimethylacetamide arefurther preferable.

The base may be either an inorganic base or an organic base. Examples ofthe inorganic bases include alkali metal hydrides such as sodium hydrideand lithium hydride; alkaline earth metal hydrides such as calciumhydride; alkali metal hydroxides such as sodium hydroxide and potassiumhydroxide; alkali metal or alkaline earth metal carbonates orhydrogencarbonates such as sodium carbonate, potassium carbonate, sodiumhydrogencarbonate and potassium hydrogencarbonate; and alkali metal oralkaline earth metal halides such as potassium fluoride, cesium fluorideand potassium iodide.

Examples of the organic bases include alkali metal alkoxides such assodium methoxide, lithium methoxide, sodium ethoxide, lithium ethoxide,sodium tertiary-butoxide and potassium tertiary-butoxide; trialkylaminessuch as triethylamine and ethyldiisopropylamine; aniline derivativescarrying alkyl groups having from 1 to 4 carbon atoms such asN,N-dimethylaniline and N,N-diethylaniline; pyridine derivativesoptionally substituted by alkyl groups having from 1 to 4 carbon atomssuch as pyridine and 2,6-lutidine; and nitrogen-containing heterocycliccompounds such as 1,8-diazabicyclo[5.4.0]undec-7-ene.

Among these bases, it is preferable to use alkali metal alkoxides,nitrogen-containing heterocyclic compounds and alkali metal or alkalineearth metal hydroxides. Potassium tertiary-butoxide,1,8-diazabicyclo[5.4.0]undec-7-ene and alkali hydroxides are stillpreferable and potassium hydroxide is further preferable. Alkalihydroxides, in particular, potassium hydroxide can be adequately used,since no isomerization proceeds during the reaction in such a case.

The base may be used in an amount of from 1 to 15 times by mol,preferably from 1 to 3 times, as much based on the molar number of theester compound of the compound (IV).

In this reaction, the yield can be elevated by adding an additive.Examples of the additive include phase transfer catalysts and molecularsieves.

Examples of the phase transfer catalysts include quaternary ammoniumsalts such as tetra (normal-hexyl) ammonium chloride,trimethylbenzylammonium chloride, triethylbenzylammonium chloride,trimethylphenylammonium chloride and tetrabutylammonium hydrogensulfate;and crown ethers such as 18-crown-6,15-crown-5.

As the additive, a phase transfer catalyst is preferable. Among all, alipophilic quaternary ammonium salt is still preferable.

Among these phase transfer catalysts, quaternary ammonium salts such astetra(normal-hexyl)ammonium chloride, trimethylbenzylammonium chloride,triethylbenzylammonium chloride, trimethylphenylammonium chloride andtetrabutylammonium hydrogensulfate are preferable.

The phase transfer catalyst may be used in an amount of from 1% to 100%,still preferably from about 3% to 30%, based on the molar number of thecompound (II).

Although the reaction temperature varies depending on the solvent used,it usually ranges from −78° C. to the boiling point of the solvent,preferably from room temperature to 60° C. and still preferably aroundroom temperature.

The reaction time ranges from 1 to 24 hours. Usually, the reaction iscompleted within about 1 to 12 hours.

The compound (V) which is the obtained product can be used as such inthe subsequent step without isolation. Namely, the steps from thecompound (IV) to the compound (VI) can be continuously carried out.

Step from Compound (V) to Compound (VI)

The compound represented by the formula (VI) can be obtained by theintramolecular cyclization of the compound represented by the formula(V). This step may be carried out by treating in a solvent in thepresence of a base and a phase transfer catalyst.

The base may be either an organic base or an inorganic base. Examples ofthe inorganic bases include alkali metal hydrides such as sodium hydrideand lithium hydride; alkaline earth metal hydrides such as calciumhydride; alkali metal hydroxides such as sodium hydroxide and potassiumhydroxide; alkali metal or alkaline earth metal carbonates orhydrogencarbonates such as sodium carbonate, potassium carbonate, sodiumhydrogencarbonate and potassium hydrogencarbonate; and alkali metal oralkaline earth metal halides such as potassium fluoride, cesium fluorideand potassium iodide.

Examples of the organic bases include alkali metal alkoxides such assodium methoxide, lithium methoxide, sodium ethoxide, lithium ethoxide,sodium tertiary-butoxide and potassium tertiary-butoxide; trialkylaminessuch as triethylamine and ethyldiisopropylamine; N,N-dialkylanilinederivatives carrying alkyl groups having from 1 to 4 carbon atoms suchas N,N-dimethylaniline and N,N-diethylaniline; pyridine derivativesoptionally substituted by alkyl groups having from 1 to 4 carbon atomssuch as pyridine and 2,6-lutidine; and nitrogen-containing heterocycliccompounds such as 1,8-diazabicyclo[5.4.0]undec-7-ene.

As the base, it is preferable to use alkali metal or alkaline earthmetal hydroxides or alkyl metal alkoxides. Potassium hydroxide andpotassium tertiary-butoxide are still preferable and potassium hydroxideis further preferable.

The base may be used in an amount of from 0.1 to 15 times by mol,preferably from 1 to 3 times, as much based on the molar number of theester compound of the compound (V).

The reaction in this step can be promoted by carrying out in thepresence of a phase transfer catalyst.

Examples of the phase transfer catalyst include quaternary ammoniumsalts such as tetra (normal-hexyl) ammonium chloride,trimethylbenzylammonium chloride, triethylbenzylammonium chloride,trimethylphenylammonium chloride and tetrabutylammonium hydrogensulfate;and crown ethers such as 18-crown-6,15-crown-5.

Among these phase transfer catalysts, quaternary ammonium salts such astetra (normal-hexyl) ammonium chloride, trimethylbenzylammoniumchloride, triethylbenzylammonium chloride, trimethylphenylammoniumchloride and tetrabutylammonium hydrogensulfate are preferable.

The phase transfer catalyst may be used in an amount of from 1% to 100%,still preferably from about 3% to 30%, based on the molar number of thecompound (IV).

The solvent is not particularly restricted so long as it exerts noundesirable effect on the reaction. Examples thereof include aliphatichydrocarbon solvents such as n-hexane, and n-pentane; aromatichydrocarbon solvents such as benzene, toluene and xylene; halogenatedhydrocarbons such as chloroform, methylene chloride and1,2-dichloroethane; ether solvents such as diethyl ether, diisopropylether, methyl t-butyl ether, tetrahydrofuran and 1,4-dioxane; ketonesolvents such as acetone and methyl ethyl ketone; amide solvents such asN,N-dimethylformamide and N,N-dimethylacetamide; halogenated hydrocarbonsolvents such as dichloromethane and chloroform; ester solvents such asmethyl acetate and ethyl acetate; and alcohol solvents such as methanol,ethanol, propanol, isopropanol, n-butanol and t-butanol. In addition,use can be also made of water, acetonitrile, acetic acid esters,acetone, etc. Either one of these solvents or a mixture of several typesthereof may be used.

As the solvent, aromatic hydrocarbon solvents, amide solvents, ketonesolvents and halogenated hydrocarbon solvents are preferable andtoluene, N,N-dimethylformamide, N,N-diemthylacetamide, acetone anddichloromethane are still preferable. Among these solvents, amidesolvents such as N,N-dimethylformamide and N,N-dimethylacetamide arefurther preferable.

Although the reaction temperature varies depending on the solvent used,it usually ranges from −78° C. to the boiling point of the solvent,preferably from 40° C. to 80° C. and still preferably around 60° C.

The reaction time ranges from 1 to 24 hours. Usually, the reaction iscompleted within about 1 to 16 hours.

Continuous Step from Compound (IV) to Compound (VI)

The compound (VI) can be obtained at once by mixing the compound (IV)with a methylenemalonic acid dialkyl ester derivative and treating inthe presence of a base. By this method, namely, the compound (VI) issynthesized from the compound (IV) at once without isolating thecompound (V). In both of these two steps, the reactions can be performedby using a phase transfer catalyst. The products in the respective stepscan be obtained each at a high yield and a high purity by performing thestep for obtaining the compound (V) at room temperature and performingthe step of the cyclization of the compound (V) under heating to about60° C.

The methylenemalonic acid dialkyl ester derivative may be used in anamount of from 1 to 4 times (by mol), preferably from 1.5 to 3 times, asmuch based on the molar number of the compound (IV).

The solvent is not particularly restricted so long as it exerts noundesirable effect on the reaction. Examples thereof include aromatichydrocarbon solvents such as benzene, toluene and xylene; ether solventssuch as diethyl ether, tetrahydrofuran and 1,4-dioxane; ketone solventssuch as acetone and methyl ethyl ketone; amide solvents such asN,N-dimethylformamide and N,N-dimethylacetamide; halogenated hydrocarbonsolvents such as dichloromethane and chloroform; ester solvents such asmethyl acetate and ethyl acetate; and alcohol solvents such as methanol,ethanol and isopropanol.

As the solvent, aromatic hydrocarbon solvents, amide solvents, ketonesolvents and halogenated solvents are preferable and toluene,N,N-dimethylformamide, N,N-diemthylacetamide, acetone anddichloromethane are still preferable.

The base may be either an organic base or an inorganic base. Examples ofthe inorganic bases include alkali metal hydrides such as sodium hydrideand lithium hydride; alkaline earth metal hydrides such as calciumhydride; alkali metal hydroxides such as sodium hydroxide and potassiumhydroxide; alkali metal or alkaline earth metal carbonates orhydrogencarbonates such as sodium carbonate, potassium carbonate, sodiumhydrogencarbonate and potassium hydrogencarbonate; and alkali metal oralkaline earth metal halides such as potassium fluoride, cesium fluorideand potassium iodide.

Examples of the organic bases include alkali metal alkoxides such assodium methoxide, lithium methoxide, sodium ethoxide, lithium ethoxide,sodium tertiary-butoxide and potassium tertiary-butoxide; trialkylaminessuch as triethylamine and ethyldiisopropylamine; N,N-dialkylanilinederivatives carrying alkyl groups having from 1 to 4 carbon atoms suchas N,N-dimethylaniline and N,N-diethylaniline; pyridine derivativesoptionally substituted by alkyl groups having from 1 to 4 carbon atomssuch as pyridine and 2,6-lutidine; and nitrogen-containing heterocycliccompounds such as 1,8-diazabicyclo[5.4.0]undec-7-ene.

Among these bases, it is preferable to use alkyl metal alkoxides,nitrogen-containing heterocyclic compounds and alkali metal or alkalineearth metal hydroxides. Potassium tertiary-butoxide,1,8-diazabicyclo[5.4.0]undec-7-ene and alkali hydroxides are stillpreferable and potassium hydroxide is further preferable.

The base may be used in an amount of from 2 to 6 times by mol,preferably from 2 to 4 times, as much based on the molar number of theester compound of the compound (IV).

In this reaction, the yield can be elevated by adding an additive.Examples of the additive include phase transfer catalysts and molecularsieves.

Examples of the phase transfer catalysts include quaternary ammoniumsalts such as tetra (normal-hexyl) ammonium chloride and tetra(normal-hexyl) ammonium iodide; and crown ethers such as18-crown-6,15-crown-5.

As the additive, a phase transfer catalyst is preferable. Among all, alipophilic quaternary ammonium salt is still preferable.

The phase transfer catalyst may be used in an amount of from 1 to 100%,still preferably from about 5 to 30%, based on the molar number of thecompound (IV).

Although the reaction temperature is not particularly restricted so longas it does not exceed the boiling point of the solvent, it preferablyranges from room temperature to 60° C.

Although the reaction time varies depending on the reaction temperature,it may range from 1 hour to 3 days.

In case where the two steps are carried out continuously, for example,the phase transfer catalyst is added in the presence of a base(potassium hydroxide, etc., 1.5 time by mol as much based on the molarnumber of the compound (IV)) and the mixture is stirred at roomtemperature for about 1 hour. Next, the liquid reaction mixture isheated to 60° C. and base is added in the same amount as describedabove. After stirring for about 5 hours, the desired compound can beobtained. That is to say, the compound (V) is once formed by stirring atroom temperature and then the base is added and the reaction temperatureis elevated. Thus, the process until the cyclization reaction can becompleted at once.

Step from Compound (IV) to Compound (VII)

The compound (VII) can be obtained by treating the compound (IV) in thepresence of a base to thereby effect intramolecular cyclization.

The base to be used herein may be either an inorganic base or an organicbase. Examples of the inorganic bases include alkali metal hydrides suchas sodium hydride and lithium hydride; alkaline earth metal hydridessuch as calcium hydride; alkali metal hydroxides such as sodiumhydroxide and potassium hydroxide; alkali metal or alkaline earth metalcarbonates or hydrogencarbonates such as sodium carbonate, potassiumcarbonate, sodium hydrogencarbonate and potassium hydrogencarbonate; andalkali metal or alkaline earth metal halides such as potassium fluoride,cesium fluoride and potassium iodide.

Examples of the organic bases include alkali metal or alkaline earthmetal alkoxides such as sodium methoxide, lithium methoxide, magnesiummethoxide, sodium ethoxide, lithium ethoxide, magnesium ethoxide, sodiumtertiary-butoxide and potassium tertiary-butoxide; alkyl lithiums suchas n-butyllithium, methyl lithium and lithium diisopropylamide;trialkylamines such as triethylamine and ethyldiisopropylamine; anilinederivatives carrying alkyl groups having from 1 to 4 carbon atoms suchas N,N-dimethylaniline and N,N-diethylaniline; pyridine derivativesoptionally substituted by alkyl groups having from 1 to 4 carbon atomssuch as pyridine and 2,6-lutidine; and nitrogen-containing heterocycliccompounds such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and1,8-diazabicyclo[4.3.0]nona-5-ene (DBN).

Among these bases, it is preferable to use alkali metal or alkalineearth metal carbonates, alkali metal hydroxides, alkyl metal alkoxidesand metal hydrides. More particularly, potassium carbonate, sodiumhydroxide, potassium tertiary-butoxide, sodium tertiary-butoxide(t-BuONa) and sodium hydride are still preferable.

The base may be used in an amount of from 1 to 15 times by mol,preferably from about 1 to 3 times, as much based on the molar number ofthe ester compound of the compound (IV).

In case of using an alkali metal or an alkali metal carbonate or analkali metal hydroxide, it is preferable to use an additive. Examples ofthe additive include phase transfer catalysts and molecular sieves.Examples of the phase transfer catalysts include quaternary ammoniumsalts such as tetra(normal-hexyl)ammonium chloride,tetra(normal-hexyl)ammonium iodide, tetrabutylammonium bromide andbenzyltriethylammonium chloride. It is also possible to carry out theinvention in the presence of an alkali metal or alkaline earth metaliodide such as potassium iodide or sodium iodide and a crown ether suchas 18-crown-6,15-crown-5.

As the additive, a phase transfer catalyst is preferable. Among all, alipophilic quaternary ammonium salt is still preferable.

The additive may be used in an amount of from 1 to 100%, preferably from5 to 30%, based on the molar number of the compound (IV).

The solvent is not particularly restricted so long as it exerts noundesirable effect on the reaction. Examples thereof include aromatichydrocarbon solvents such as benzene, toluene and xylene; aliphatichydrocarbon solvents such as n-hexane, n-pentane and cyclohexane; ethersolvents such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane,methyl t-butyl ether (MTBE), tetrahydrofuran and 1,4-dioxane; ketonesolvents such as acetone and methyl ethyl ketone; amide solvents such asN,N-dimethylformamide and N,N-dimethylacetamide; halogenated hydrocarbonsolvents such as dichloromethane and chloroform; ester solvents such asmethyl acetate and ethyl acetate; and alcohol solvents such as methanol,ethanol, isopropanol, n-butanol and t-butanol.

As the solvent, amide solvents are preferable and N,N-dimethylformamideand N,N-diemthylacetamide are still preferable.

The reaction temperature is not particularly restricted but usuallyranges from −78° C. to the boiling point of the solvent. It preferablyranges from room temperature to the boiling point of the solvent.

Although the reaction time varies depending on the reaction temperature,it may range from 15 minutes to 12 hours.

The compound (VII) thus obtained can be purified by forming a salttogether with a compound represented by the following formula:R¹¹—SO₃H[wherein R¹¹ represents a phenyl group (which may have one or moregroups of one or more types selected from the group consisting ofhalogen atoms, alkyl groups having from 1 to 6 carbon atoms,halogenoalkyl groups having from 1 to 6 carbon atoms, alkoxy groupshaving from 1 to 6 carbon atoms, nitro group, carbamoyl group and cyanogroup), a camphor group (which may have one or more groups of one ormore types selected from the group consisting of halogen atoms, nitrogroup, carbamoyl group, cyano group, alkyl groups having from 1 to 6carbon atoms, halogenoalkyl groups having from 1 to 6 carbon atoms andalkoxy groups having from 1 to 6 carbon atoms), an alkyl group havingfrom 1 to 6 carbon atoms or a halogenoalkyl group having from 1 to 6carbon atoms].Since an optically active isomer of the compound (VII) is an oilysubstance, the purity of the final product levofloxacin can be elevatedby the purification by forming such a salt as described above.

Among these sulfonic acids, methanesulfonic acid, para-toluenesulfonicacid and camphorsulfonic acid are preferable.

Examples of the solvent to be used in the formation of the salt includehydrocarbon solvents such as n-hexane and n-pentane; aromatichydrocarbon solvents such as benzene, toluene and xylene; alcoholsolvents such as methanol, ethanol, propanol, isopropanol, n-butanol andt-butanol; ether solvents such as diethyl ether, diisopropyl ether,methyl t-butylether, tetrahydrofuran, 1,2-dimethoxyethane and1,4-dioxane; amide solvents such as N,N-dimethylformamide andN,N-dimethylacetamide; and halogenated hydrocarbon solvents such aschloroform, methylene chloride and 1,2-dichloroethane. In addition, usecan be also made of water, acetonitrile, acetic acid esters, acetone,etc. Either one of these solvents or a mixture of several types thereofmay be used.

Among these solvents, aromatic hydrocarbon solvents such as toluene,acetic cid esters and acetone are preferable.

The solvent may be used usually in an amount of from about 1 to 100times by weight, preferably from about 2 to 50 times by weight, as much.

Although the temperature for the crystallization of the target salt isnot constant, temperature conditions commonly used in the art may beused therefor. More particularly speaking, it may be carried out withina temperature range from ice-cooling to the boiling point of the solventused. The salt may be formed in the following manner. After thecompletion of the cyclization reaction to give the compound (VII), thesolvent is replaced by another solvent to be used in the salt formationand then sulfonic acid is added. It is needless to say that the liquidreaction mixture after the cyclization may be treated and isolated inthe conventional manner to thereby form the salt.

The salt thus formed can be converted into a free compound by treatingwith an alkali. For example, use can be made of bases including alkalimetal hydroxides such as sodium hydroxide and potassium hydroxide,alkali metal carbonates such as sodium carbonate and potassiumcarbonate, and alkali metal hydrogencarbonate such as sodiumhydrogencarbonate and potassium hydrogencarbonate. Such a base isusually used in the form of an aqueous solution and the free compoundcan be isolated by extraction, etc.

Step from Compound (VII) to Compound (VI)

The compound (VI) can be obtained by reacting the compound (VII) with amethylenemalonic acid dialkyl ester derivative.

In this step, the compound (VI) can be obtained by adding themethylenemalonic acid dialkyl ester derivative to the compound (VII) andheating, or treating the compound (VII) and the methylenemalonic aciddialkyl ester derivative in a solvent in the presence of a base.

(1) Method of Adding Methylenemalonic Acid Dialkyl Ester Derivative toCompound (VII) Followed by Heating

The methylenemalonic acid dialkyl ester derivative may be used in anamount from 1 to 3 times by mol, preferably from 1.1 to 1.6 time, asmuch based on the molar number of the compound (VII).

The reaction can be performed either without using a solvent or in asolvent. As the solvent, use can be made of any one so long as it exertsno effect on the reaction. Examples thereof include aromatic hydrocarbonsolvents such as toluene and xylene.

It is preferable to perform the reaction without using a solvent orusing an aromatic hydrocarbon solvent such as toluene or xylene.

The reaction temperature is not particularly restricted so long as itdoes not exceed the boiling point of the solvent.

It preferably ranges from 100° C. to 160° C. Although the reaction timevaries depending on the reaction temperature, it is usually completedwithin 1 hour to 1 day.

(2) Method of Treating Compound (VII) and Methylenemalonic Acid DialkylEster Derivative in Solvent in the Presence of Base and Phase TransferCatalyst

The methylenemalonic acid dialkyl ester derivative may be used in anamount from 1 to 3 times by mol, preferably from 1.05 to 2 times, asmuch based on the molar number of the compound (VII).

The solvent is not particularly restricted so long as it exerts noundesirable effect on the reaction. Examples thereof include aromatichydrocarbon solvents such as benzene, toluene and xylene; ether solventssuch as diethyl ether, tetrahydrofuran and 1,4-dioxane; ketone solventssuch as acetone and methyl ethyl ketone; amide solvents such asN,N-dimethylformamide and N,N-dimethylacetamide; halogenated hydrocarbonsolvents such as dichloromethane and chloroform; ester solvents such asmethyl acetate and ethyl acetate; and alcohol solvents such as methanol,ethanol and isopropanol.

Among these solvents, aromatic hydrocarbon solvents, amide solvents,ketone solvents and halogenated solvents are preferable and toluene,N,N-dimethylformamide, acetone and dichloromethane are still preferable.

The base may be either an organic base or an inorganic base. Examples ofthe inorganic bases include alkali metal hydrides such as sodium hydrideand lithium hydride; alkaline earth metal hydrides such as calciumhydride; alkali metal alkoxides such as sodium methoxide, lithiummethoxide, sodium ethoxide, lithium ethoxide, sodium tertiary-butoxideand potassium tertiary-butoxide; alkali metal hydroxides such as sodiumhydroxide and potassium hydroxide; alkali metal or alkaline earth metalcarbonates or hydrogencarbonates such as sodium carbonate, potassiumcarbonate, sodium hydrogencarbonate and potassium hydrogencarbonate; andalkali metal or alkaline earth metal halides such as potassium fluoride,cesium fluoride and potassium iodide.

Examples of the organic bases include trialkylamines such astriethylamine and ethyldiisopropylamine; aniline derivatives carryingalkyl groups having from 1 to 4 carbon atoms such as N,N-dimethylanilineand N,N-diethylaniline; pyridine derivatives optionally substituted byalkyl groups having from 1 to 4 carbon atoms such as pyridine and2,6-lutidine; and nitrogen-containing heterocyclic compounds such as1,8-diazabicyclo[5.4.0]undec-7-ene.

As the base, alkyl metal alkoxides is preferable and potassiumtertiary-butoxide is still preferable.

The base may be used in an amount of from 1 to 3 times by mol,preferably from 1 to 2 times, as much based on the molar number of theester compound of the compound (VII).

Although the reaction time varies depending on the reaction temperature,it is usually completed within 1 hour to 1 day.

By carrying out the processes as described above, the compound (VI) canbe produced from the compound (I). It is expected that the followingstep can be also used therefor in addition to these processes.

The compound (VI-a) thus obtained can be converted into levofloxacin bya known method. Now, the method will be briefly described. Namely, thecompound (VI-a) is subjected to cyclization by heating together withpolyphosphoric acid or its ester to give a tricyclic carboxylic acidester compound. Next, this carboxylic acid ester is hydrolyzed underbasic or acidic conditions to give a tricyclic carboxylic acid compound.This tricyclic carboxylic acid compound is then reacted with4-methylpiperazine in the presence of a base and thus levofloxacin canbe obtained. The base may be either an inorganic base or an organicbase. Examples of the inorganic base include alkali metal or alkalineearth metal carbonates and hydrogencarbonates. Examples of the organicacids include trialkylamines and nitrogen-containing heterocycliccompounds. More particularly speaking, triethylamine, tributylamine,ethyldiisopropylamine, etc. or 4-methylmorpholine,dimethylaminopyridine, etc., or 4-methylpiperazine may be used in excessto thereby make it to serve as a base too. It is favorable to use asolvent in this reaction and dimethyl sulfoxide is usable as thesolvent. In the reaction of 4-methylpiperazine, it is more effective touse not the tricyclic carboxylic acid compound but a dihalogenoboronchelate compound of this carboxylic acid. This dihalogenoboron chelatecompound may be obtained by reacting the tricyclic carboxylic acidcompound with a trihalogenoboron compound. It is convenient to use acomplex of the trihalogenobron compound with an ether compound, forexample, a diethyl ether complex or a tetrahydrofuran complex. As thehalogen atom, fluorine atom is preferable. By stirring this ethercomplex with the carboxylic acid in various ether solvents, adihalogenoborn chelate compound of the carboxylic acid can be obtained.The reaction with 4-methylpiperazine may be carried out in a solvent inthe presence of a base similar to the above-described case. Thedihalogenoboron chelate compound of the carboxylic acid can be obtainedin a single step by heating the compound (VI-a), a dihalogenoboroncompound (preferably a complex with an ether compound) in a solvent (forexample, acetic anhydride). After the completion of the reaction with4-methylpiperazine, it is necessary to eliminate (hydrolyze) thechelate. It can be performed by heating in an aprotic solvent in thepresence of a base to thereby cleave and eliminate. For example, it maybe cited to heat in an alcohol solvent in the presence of atrialkylamine. More particularly speaking, it may be heated and stirredin ethanol in the presence of triethylamine.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, the present invention will be illustrated in greater detail byreference to the following Examples. However, it is to be understoodthat the present invention is not construed as being restricted thereto.

EXAMPLE 1 Methyl (2S)-2-(2,3,4-trifluoroanilino)propionate

Under ice-cooling, methyl D-lactate (8.5 g) and 2,6-lutidine (11.4 g)were dissolved in dichloromethane (100 ml). After dropping anhydroustrifluoromethanesulfonic acid (25.4 g), the mixture was heated to roomtemperature and stirred for 30 minutes. Then it was cooled to 0° C.again and a solution (30 ml) of 2,3,4-trifluoroaniline (12.0 g) indichloromethane was dropped thereinto. The mixture was stirred at thesame temperature for 17 hours. To the resultant solution, hydrochloricacid (0.5 mol/l) was added and the mixture was extracted withdichloromethane. The extract was washed with a saturated aqueoussolution of sodium chloride, dried over magnesium sulfate and filtered.After evaporating the solvent, the residue thus obtained was subjectedto silica gel column chromatography. Thus, 17.1 g (90%) of the titlecompound was obtained as an oily substance. The optical puritydetermined by HPLC was 97% ee.

¹H-NMR (CDCl₃, 270 MHz) δ: 1.51 (d, J=6.9 Hz, 3H), 3.73 (s, 3H),4.07–4.13 (m, 1H), 4.22 (brs, 1H), 6.22–6.31 (m, 1H), 6.73–6.85 (m, 1H)

IR (nujol): 3407, 2994, 2956, 1739 cm⁻¹

MS; m/z: 233 (M⁺)

EXAMPLE 2 Methyl (2S)-2-(2,3,4-trifluoroanilino)propionate

2,3,4-Trifluoroaniline (100 mg) was dissolved in toluene (1 ml). Afteradding potassium carbonate (188 mg), methyl(2R)-2-[[(4-methylphenyl)sulfonyl]oxy]propionate (193 mg) andtetrahexylammonium chloride (40 mg), the mixture was stirred underheating and refluxing for 15.5 hours. After treating as in Example 1,the obtained product was analyzed by reversed phase HPLC with the use ofthe compound of Example 1 as a specimen. As a result, the productcorresponded to 41 mg (26%) of the title compound.

EXAMPLE 3 Methyl (2S)-2-(2,3,4-trifluoroanilino)propionate

In accordance with the process of Example 2, a condensation reaction wasperformed by using 2,3,4-trifluoroaniline (100 mg), potassium carbonate(188 mg), methyl (2R)-2-[(methanesulfonyl)oxy]propionate (78 mg) andtetrahexylammonium chloride (40 mg) to give the title compound as anoily substance. As the result of the analysis by reversed phase HPLCwith the use of the compound of Example 1 as a specimen, the productcorresponded to 38 mg (24%) of the title compound.

EXAMPLE 4 Methyl (2S)-2-(2,3,4-trifluoroanilino)propionate

In accordance with the process of Example 2, a condensation reaction wasperformed by using 2,3,4-trifluoroaniline (100 mg), potassium carbonate(188 mg), methyl (2R)-chloropropionate (92 mg) and tetrahexylammoniumchloride (40 mg). As the result of the analysis by reversed phase HPLCwith the use of the compound of Example 1 as a specimen, the productcorresponded to 56 mg (36%) of the title compound.

EXAMPLE 5 Methyl 2-(2,3,4-trifluoroanilino)propionate

2,3,4-Trifluoronitrobenzene (100 g) and methyl pyruvate (57.6 g) weredissolved in methanol (1000 ml). After adding 5% Pd—C (20.0 g) andanhydrous magnesium sulfate (90 g), the mixture was stirred at roomtemperature in a hydrogen atmosphere for 16 hours. Then the liquidreaction mixture was filtered through celite to thereby eliminate Pd—Cand magnesium sulfate. The obtained filtrate was concentrated underreduced pressure and Florisil (100 g) and diethyl ether (700 ml) wereadded to the residue. After stirring for 2 hours, the liquid reactionmixture was filtered. The obtained organic layer was evaporated and thecrystals thus precipitated were filtered while washing with hexane. Thusthe title compound (128.2 g) was obtained as slightly yellowishcrystals.

Melting point: 41 to 43° C.

¹H-NMR (CDCl₃) δ: 1.51 (d, J=6.9 Hz, 3H), 3.74 (s, 3H), 4.0–4.3 (m, 2H),6.2–6.4 (m, 1H), 6.7–6.9 (m, 1H)

IR (KBr): 3357, 1719, 1510 cm⁻¹

Elemental analysis as C₁₀H₁₀NO₂F₃

Calculated (%): C, 51.51; H, 4.32; N, 6.01. Found (%): C, 51.65; H,4.31; N, 5.99.

EXAMPLE 6 Methyl 2-(2,3,4-trifluoroanilino)propionate

2,3,4-Trifluoroaniline (2.94 g) and methyl pyruvate (2.04 g) weredissolved in methanol (30 ml). After adding 5% Pd—C (2.0 g) andanhydrous magnesium sulfate (2.65 g), the mixture was stirred at 50° C.in a hydrogen atmosphere for 16 hours. After filtering off Pd—C andmagnesium sulfate, the obtained filtrate was concentrated under reducedpressure. The crystals thus precipitated were filtered while washingwith hexane. Thus the title compound (4.44 g) was obtained as slightlyyellowish crystals. Various spectral data of this product was identicalwith those obtained in Example 5.

EXAMPLE 7 Ethyl 2-(2,3,4-trifluoroanilino)propionate

2,3,4-Trifluoronitrobenzene (3.54 g) and methyl pyruvate (2.32 g) weredissolved in ethanol (30 ml). After adding 5% Pd—C (2.0 g) and anhydrousmagnesium sulfate (2.65 g), the mixture was stirred at 50° C. in ahydrogen atmosphere for 16 hours. After filtering off Pd—C and magnesiumsulfate, the obtained filtrate was concentrated under reduced pressure.The residue thus obtained was subjected to silica gel columnchromatography (ethyl acetate-normal hexane=1:4) to give the titlecompound (4.84 g) as a pale yellow oily substance.

¹H-NMR (CDCl₃) δ: 1.25 (t, J=7.1 Hz, 3H), 1.50 (d, J=7.1 Hz, 3H),4.0–4.3 (m, 2H), 4.19 (dd, J=7.3, 10.9 Hz, 3H), 6.2–6.4 (m, 1H), 6.7–6.9(m, 1H)

IR (cm⁻): 1737, 1524, 909

EXAMPLE 8 Ethyl 2-(2,3,4-trifluoroanilino)propionate

2,3,4-Trifluoroaniline (2.94 g) and ethyl pyruvate (2.32 g) weredissolved in methanol (30 ml). After adding 5% Pd—C (2.0 g) andanhydrous magnesium sulfate (2.65 g), the mixture was stirred at 50° C.in a hydrogen atmosphere for 16 hours. After filtering off Pd—C andmagnesium sulfate, the obtained filtrate was concentrated under reducedpressure. The obtained residue was subjected to silica gel columnchromatography (ethyl acetate-normal hexane=1:4) to thereby give thetitle compound (4.69 g) as a pale yellow oily substance. Variousspectral data of this product was identical with those obtained inExample 7.

EXAMPLE 9 Methyl 2-(2,3,4-trifluoroanilino)propionate

2,3,4-Trifluoroaniline (1.01 g) and methyl pyruvate (0.87 g) weredissolved in methanol (8 ml). After adding 5% Pd—C (0.11 g) and conc.hydrochloric acid (0.03 g), the mixture was stirred at 40° C. under ahydrogen gas pressure of 2.94 MPa (converted from 30 kgf/cm²) for 2hours. After filtering off Pd—C, the obtained filtrate was concentratedunder reduced pressure. Thus the title compound (1.31 g) was obtained asslightly yellowish crystals. Various spectral data of this product wasidentical with those obtained in Example 5.

EXAMPLE 10 Ethyl 2-(2,3,4-trifluoroanilino)propionate

2,3,4-Trifluoronitrobenzene (1.01 g) and ethyl pyruvate (1.15 g) weredissolved in ethanol (8 ml). After adding 5% Pd—C (0.11 g) and conc.hydrochloric acid (0.03 g), the mixture was stirred at 40° C. under ahydrogen gas pressure of 2.94 MPa for 3 hours. After filtering off Pd—C,the obtained filtrate was concentrated under reduced pressure. Thus thetitle compound (1.38 g) was obtained as slightly yellow oily substance.Various spectral data of this product was identical with those obtainedin Example 7.

EXAMPLE 11 Methyl 2-(2,3,4-trifluoroanilino)propionate

2,3,4-Trifluoroaniline (0.83 g) and methyl pyruvate (0.87 g) weredissolved in methanol (8 ml). After adding 5% Pd—C (0.11 g) and conc.hydrochloric acid (0.03 g), the mixture was stirred at 40° C. under ahydrogen gas pressure of 2.94 MPa for 2 hours. After filtering off Pd—C,the obtained filtrate was concentrated under reduced pressure. Thus thetitle compound (1.26 g) was obtained as slightly yellowish crystals.Various spectral data of this product was identical with those obtainedin Example 5.

EXAMPLE 12 Ethyl 2-(2,3,4-trifluoroanilino)propionate

2,3,4-Trifluoroaniline (0.83 g) and ethyl pyruvate (1.15 g) weredissolved in ethanol (8 ml). After adding 5% Pd—C (0.11 g) and conc.hydrochloric acid (0.03 g), the mixture was stirred at 40° C. under ahydrogen gas pressure of 2.94 MPa for 3 hours. After filtering off Pd—C,the obtained filtrate was concentrated under reduced pressure. Thus thetitle compound (1.32 g) was obtained as slightly yellow oily substance.Various spectral data of this product was identical with those obtainedin Example 7.

EXAMPLE 13 2-(2,3,4-Trifluoroanilino)propionic acid

2,3,4-Trifluoronitrobenzene (5.03 g) and pyruvic acid (2.75 g) weredissolved in isopropanol (IPA; 40 ml). After adding 10% Pd—C (0.21 g),the mixture was stirred at 40° C. under atmospheric pressure in ahydrogen atmosphere for 3 hours. After filtering off Pd—C, the obtainedfiltrate was concentrated under reduced pressure. Thus the titlecompound (6.11 g) was obtained as colorless crystals. Various spectraldata of this product was identical with those of a specimen synthesizedseparately.

EXAMPLE 14 2-(2,3,4-Trifluoroanilino)propionic acid

2,3,4-Trifluoronitrobenzene (5.03 g) and pyruvic acid (2.75 g) weredissolved in IPA (40 ml). After adding 10% Pd—C (0.21 g), the mixturewas stirred at 40° C. under a hydrogen gas pressure of 2.94 MPa for 3hours. After filtering off Pd—C, the obtained filtrate was concentratedunder reduced pressure. Thus the title compound (6.09 g) was obtained ascolorless crystals. Various spectral data of this product was identicalwith those of a specimen synthesized separately.

EXAMPLE 15 2-(2,3,4-Trifluoroanilino)propionic acid

2,3,4-Trifluoronitrobenzene (1.01 g) and pyruvic acid (0.75 g) weredissolved in methanol (8 ml). After adding 5% Pd—C (0.11 g), the mixturewas stirred at 40° C. under a hydrogen gas pressure of 4.9 MPa(converted from 50 kgf/cm²) for 5 hours. After filtering off Pd—C, theobtained filtrate was concentrated under reduced pressure. Thus thetitle compound (1.20 g) was obtained as colorless crystals. Variousspectral data of this product was identical with those of a specimensynthesized separately.

EXAMPLE 16 2-(2,3,4-Trifluoroanilino)propionic acid

2,3,4-Trifluoroaniline (4.18 g) and pyruvic acid (2.75 g) were dissolvedin IPA (40 ml). After adding 10% Pd—C (0.21 g), the mixture was stirredat 40° C. under atmospheric pressure in a hydrogen atmosphere for 3hours. After filtering off Pd—C, the obtained filtrate was concentratedunder reduced pressure. Thus the title compound (5.69 g) was obtained ascolorless crystals. Various spectral data of this product was identicalwith those of a specimen synthesized separately.

EXAMPLE 17 N-(1-Methoxycarbonylethylidene)-2,3,4-trifluoroaniline

Trifluoroaniline (1 g) and magnesium sulfate (1.36 g) were stirred inmethanol (5 ml) at room temperature. After adding methyl pyruvate (1.27g) thereto, the mixture was heated to 40° C. and stirred for 20 hours.After the completion of the reaction, magnesium sulfate was filteredoff. The filtrate thus obtained was concentrated under reduced pressureand the residue was subjected to silica gel column chromatography(hexane-diethyl ether=1:3) to thereby give the title compound (552 mg)as methanol crystals.

¹H-NMR (CDCl₃) d: 6.92–6.74 (m, 2H), 5.09 (brs, 1H), 3.84 (s, 3H), 3.24(s, 3H), 1.65 (s, 3H)

EXAMPLE 18 Methyl (2S)-2-(2,3,4-trifluoroanilino)propionate

Chloro-1,5-cyclooctadiene iridium dimer (12.8 mg) and (2S,4S)-BCPM (23.6mg) were dissolved in IPA (2 ml) under an argon gas stream and stirredat room temperature for 1 hour. To this liquid reaction mixture wasadded a solution ofN-(1-methoxycarbonylethylidene)-2,3,4-tirfluoroaniline mono-methanolcrystal (50 mg) in IPA (2 ml). The liquid reaction mixture wastransferred into an autoclave and a hydrogen pressure of 50 kg/cm² wasapplied. Then the liquid reaction mixture was stirred at 10° C. for 15hours. The chemical yield and optical purity of the title compoundcontained in the final liquid reaction mixture measured by highperformance liquid chromatography were 70% and 50% ee (S-compound)respectively.

EXAMPLES 19 to 22

By altering the optically active ligand, imino compounds wereasymmetrically reduced by the same method as the reaction describedabove. The results of these Examples are summarized in the followingTable.

TABLE Optically Reaction Chemical Asymmetric active temp. Reaction Yieldyield Ex. ligand Additive (° C.) time (h) (%) (ee %) 19 (S)-(R)- none 1015.5 19.4 63.0 JOSIPHOS 20 (2S,4S)- KI/SiO₂ 20 18.5 17.1 71.7 BCPM 21(4R,5R)- none 10 14.5 97.4 20.7 MOD-DIOP 22 (2S,4S)- zeolite 4A 20 1679.5 50.5 BCPM

-   (2S,4S)-BCPM:-   (2S,4S)-N-(t-butoxycarbonyl)-4-(dicyclohexylphosphino)-2-[(diphenylphosphino)methyl]pyrrolidine-   (S)-(R)-JOSIPHOS:-   (S)-1-[(R)-2-(diphenylphosphino)ferrocenyl]ethyldicyclohexylphosphine-   (4R,5R)-MOD-DIOP:-   (4R,5R)-4,5-bis[[bis(4′-methoxy-3′,5,-dimethylphenyl)phosphino]methyl]-2,2-dimethyl-1,3-dioxolane

EXAMPLE 23 2-(2,3,4-Trifluoroanilino)propionic acid

Methyl 2-(2,3,4-trifluoroanilino)propionate (46.64 g) was dissolved inmethanol (130 ml) and an aqueous solution (3 mol/l; 100 ml) of lithiumhydroxide was slowly added thereto at 0° C. After stirring at roomtemperature for 3 hours, the solvent was evaporated. After adding water,the residue was washed with chloroform. Next, hydrochloric acid (6mol/l) was slowly added to the aqueous layer until pH value reached 1.Then the aqueous layer was extracted with diisopropyl ether (IPE). Theorganic layer was dried over anhydrous magnesium sulfate and then thesolvent was evaporated to give the title compound (43.7 g) as colorlesscrystals.

Melting point: 114 to 119° C.

¹H-NMR (CDCl₃) δ: 1.57 (d, J=6.9 Hz, 3H), 4.11 (dd, J=6.9, 10.3 Hz, 1H),6.2–6.4 (m, 1H), 6.7–6.9 (m, 1H)

IR (cm⁻¹): 3357, 1725, 1524, 1195

Elemental analysis as C₉H₈NO₂F₃

Calculated (%): C, 49.32; H, 3.68; N, 6.39. Found (%): C, 49.33; H,3.65; N, 6.34.

EXAMPLE 24 2-(2,3,4-Trifluoroanilino)propionic acid

Ethyl 2-(2,3,4-trifluoroanilino)propionate (2.47 g) was dissolved inethanol (40 ml) and an aqueous solution (3 mol/l; 10 ml) of sodiumhydroxide was slowly added thereto at 0° C. After stirring at roomtemperature for 3 hours, the solvent was evaporated. After adding water,the residue was washed with chloroform. Next, hydrochloric acid (6mol/l) was slowly added to the aqueous layer until pH value reached 1.Then the aqueous layer was extracted with IPE. The organic layer wasdried over anhydrous magnesium sulfate and then the solvent wasevaporated to give the title compound (2.19 g) as colorless crystals.Various spectral data of this product was identical with those obtainedin Example 23.

EXAMPLE 25 (2S)-2-(2,3,4-Trifluoroanilino)propionicacid•(R)-1-phenyethylamine salt

2-(2,3,4-Trifluoroanilino)propionic acid (1.1 g) was dissolved in asolvent mixture (15 ml; methanol-IPE=1:20). At room temperature, asolution (15 ml) of (R)-1-phenylethylamine (333.2 mg) in a solventmixture (methanol-IPE=1:20) was slowly added thereto. The obtainedsuspension was stirred at room temperature for additional 2 hours andthen filtered while washing with IPE. Thus, the title compound wasobtained as colorless crystals (802 mg). The optical purity of thisproduct was 80% ee. Subsequently, chloroform was added to the obtainedsalt and the mixture was stirred at 50° C. for 18 hours. Then thesuspension was filtered while washing with IPE to give 703 mg of thetitle compound as colorless crystals. The optical purity of this productwas 99% ee.

[α]_(D)=5.7° (c=0.386, methanol)

Melting point (decomposition): 189 to 197° C.

¹H-NMR (CD₃OD) δ: 1.41 (d, J=6.9 Hz, 3H), 1.61 (d, J=6.9 Hz, 3H), 3.80(dd, J=6.9, 15.4 Hz, 1H), 4.42 (dd, J=6.9, 10.0 Hz, 1H), 6.3–6.5 (m,1H), 6.7–6.9 (m, 1H), 7.3–7.5 (m, 5H)

Elemental analysis as C₁₇H₁₉NO₂F₃

Calculated (%): C, 60.86; H, 5.96; N, 7.91. Found (%): C, 61.01; H,5.97; N, 7.85.

EXAMPLE 26 (2S)-2-(2,3,4-Trifluoroanilino)propionicacid•(R)-1-triethylamine salt

2-(2,3,4-Trifluoroanilino)propionic acid (1.1 g) was dissolved in asolvent mixture (15 ml; methanol-IPE=1:20). At room temperature, asolution (15 ml) of (R)-1-tolylethylamine (371.8 mg) in a solventmixture (methanol-IPE=1:20) was slowly added thereto. The obtainedsuspension was stirred at room temperature for additional 2 hours andthen filtered while washing with IPE. Thus, the title compound wasobtained as colorless crystals (860 mg). The optical purity of thisproduct was 52% ee. Subsequently, chloroform was added to the obtainedsalt and the mixture was stirred at 50° C. for 18 hours. Then thesuspension was filtered while washing with IPE to give 591 mg of thetitle compound as colorless crystals. The optical purity of this productwas 99% ee.

[α]_(D)=−2.0° (c=0.197, methanol)

Melting point (decomposition): 190 to 197° C.

¹H-NMR (CD₃OD) δ: 1.41 (d, J=6.9 Hz, 3H), 1.59 (d, J=6.9 Hz, 3H) 2.35(s, 3H), 3.80 (dd, J=6.9, 12.0 Hz, 1H), 4.38 (dd, J=6.9, 12.0 Hz, 1H),6.3–6.5 (m, 1H), 6.7–6.9 (m, 1H), 7.2–7.3 (m, 4H)

Elemental analysis as C₁₈H₂₁NO₂F₃

Calculated (%): C, 59.99; H, 5.63; N, 8.23. Found (%): C, 59.96; H,5.67; N, 8.16.

EXAMPLE 27 (2S)-2-(2,3,4-Trifluoroanilino)propionicacid•(S)-1-phenyl-2-p-triethylamine salt

2-(2,3,4-Trifluoroanilino)propionic acid (1.1 g) was dissolved in asolvent mixture (15 ml; methanol-IPE=1:20). At room temperature, asolution (15 ml) of (R)-1-p-tolylethylamine (581.8 mg) in a solventmixture (methanol-IPE=1:20) was slowly added thereto. The obtainedsuspension was stirred at room temperature for additional 2 hours andthen filtered while washing with IPE. Thus, the title compound wasobtained as 1.1 g of colorless crystals. The optical purity of thisproduct was 79% ee. Subsequently, chloroform was added to the obtainedsalt and the mixture was stirred at 50° C. for 18 hours. Then thesuspension was filtered while washing with IPE to give 923 mg of thetitle compound as colorless crystals. The optical purity of this productwas 99% ee.

[α]_(D)=−5.6° (c=0.386, methanol)

Melting point (decomposition): 187 to 193° C.

¹H-NMR (CD₃OD) δ: 1.41 (d, J=6.9 Hz, 3H), 2.26 (s 3H), 3.0–3.3 (m, 2H),3.81 (dd, J=6.9, 11.7 Hz, 1H), 4.43 (dd, J=6.6, 8.3 Hz), 6.3–6.5 (m,1H), 6.7–6.9 (m, 1H), 7.00 (dd, J=7.9, 21.0 Hz), 7.2–7.3 (m, 5H)

Elemental analysis as C₂₃H₂₃O₂F₃

Calculated (%): C, 66.96; H, 5.85; N, 6.51. Found (%): C, 56.85; H,5.89; N, 6.44.

EXAMPLE 28 (2S)-2-(2,3,4-Trifluoroanilino)propionic acid

To (2S)-2-(2,3,4-trifluoroanilino)propionic acid•(S)-1-phenylethylaminesalt (1.0 g; 99% ee) were added IPE (20 ml) and hydrochloric acid (1mol/l) until the pH value reached 1 and the resultant mixture wasstirred at room temperature for 1 hour. The organic layer was dried overanhydrous magnesium sulfate. After evaporating the solvent, 618 mg ofthe title compound was obtained as colorless crystals. The opticalpurity of this product was 99% ee. The ¹H-NMR and IR spectral data ofthis product was identical with those of the compound obtained inExample 23.

EXAMPLE 29 (2S)-2-(2,3,4-Trifluoroanilino)propionic acid

To (2S)-2-(2,3,4-trifluoroanilino)propionic acid•(S)-1-triethylaminesalt (1.0 g; 99% ee) were added IPE (22 ml) and hydrochloric acid (1mol/l) until the pH value reached 1 and the resultant mixture wasstirred at room temperature for 1 hour. The organic layer was dried overanhydrous magnesium sulfate. After evaporating the solvent, 645 mg ofthe title compound was obtained as colorless crystals. The opticalpurity of this product was 99% ee. The ¹H-NMR and IR spectral data ofthis product was identical with those of the compound obtained inExample 23.

EXAMPLE 30 (2S)-2-(2,3,4-Trifluoroanilino)propionic acid

To (2S)-2-(2,3,4-trifluoroanilino)propionicacid•(R)-1-phenyl-2-p-triethylamine salt (1.0 g; 99% ee) were added IPE(25 ml) and hydrochloric acid (1 mol/l) until the pH value reached 1 andthe resultant mixture was stirred at room temperature for 1 hour. Theorganic layer was dried over anhydrous magnesium sulfate. Afterevaporating the solvent, 510 mg of the title compound was obtained ascolorless crystals. The optical purity of this product was 99% ee. The¹H-NMR and IR spectral data of this product was identical with those ofthe compound obtained in Example 23.

EXAMPLE 31 Methyl (2S)-2-(2,3,4-trifluoroanilino)propionate

(2S)-2-(2,3,4-trifluoroanilino)propionic acid (1.1 g; 99% ee) wasdissolved in methanol (10 ml) and hydrochloric acid (5 mol/l; 1 ml) wasadded thereto at room temperature. The liquid reaction mixture washeated under reflux for 6 hours and then the solvent was evaporated. Tothe obtained residue was added chloroform (10 ml). Next, the organiclayer was washed with a saturated aqueous solution of sodium chlorideand water and dried over anhydrous magnesium sulfate. After evaporatingthe solvent, the obtained residue was subjected to silica gel columnchromatography (ethyl acetate-normal hexane=1:4) to give the titlecompound (1.17 g) as an oily substance. The optical purity of theproduct was 99% ee. The ¹H-NMR and IR spectral data of this product wasidentical with those of the compound obtained in Example 5.

[α]_(D)=−49.4° (c=0.119, methanol)

EXAMPLE 32 Methyl (2R)-2-(2,3,4-trifluoroanilino)propionate

(2R)-2-(2,3,4-trifluoroanilino)propionic acid (1.1 g; 98% ee) wasdissolved in methanol (10 ml) and hydrochloric acid (5 mol/l; 1 ml) wasadded thereto at room temperature. The liquid reaction mixture washeated under reflux for 6 hours and then the solvent was evaporated. Tothe obtained residue was added chloroform (10 ml). Next, the organiclayer was washed with a saturated aqueous solution of sodium chlorideand water and dried over anhydrous magnesium sulfate. After evaporatingthe solvent, the obtained residue was subjected to silica gel columnchromatography (ethyl acetate-normal hexane=1:4) to give the titlecompound (1.17 g) as an oily substance. The optical purity of theproduct was 99% ee. The ¹H-NMR and IR spectral data of this product wasidentical with those of the compound obtained in Example 5.

EXAMPLE 33 Ethyl (2S)-2-(2,3,4-trifluoroanilino)propionate

(2S)-2-(2,3,4-trifluoroanilino)propionic acid (219 mg; 99% ee) wasdissolved in ethanol (2 ml) and hydrochloric acid (5 mol/l; 0.2 ml) wasadded thereto at room temperature. The liquid reaction mixture washeated under reflux for 6 hours and then the solvent was evaporated. Tothe obtained residue was added chloroform. Next, the organic layer waswashed with a saturated aqueous solution of sodium chloride and waterand dried over anhydrous magnesium sulfate. After evaporating thesolvent, the obtained residue was subjected to silica gel columnchromatography (ethyl acetate-normal hexane=1:4) to give the titlecompound (246 mg) as a pale yellow oily substance. The optical purity ofthe product was 99% ee. The ¹H-NMR and IR spectral data of this productwas identical with those of the compound obtained in Example 7.

[α]_(D)=−57.2° (c=0.352, methanol)

EXAMPLE 34 Ethyl (2R)-2-(2,3,4-trifluoroanilino)propionate

(2R)-2-(2,3,4-trifluoroanilino)propionic acid (219 mg; 99% ee) wasdissolved in ethanol (2 ml) and hydrochloric acid (5 mol/l; 0.2 ml) wasadded thereto at room temperature. The liquid reaction mixture washeated under reflux for 6 hours and then the solvent was evaporated. Tothe obtained residue was added chloroform (10 ml). Next, the organiclayer was washed with a saturated aqueous solution of sodium chlorideand water and dried over anhydrous magnesium sulfate. After evaporatingthe solvent, the obtained residue was subjected to silica gel columnchromatography (ethyl acetate-normal hexane=1:4) to give the titlecompound (245 mg) as a pale yellow oily substance. The optical purity ofthe product was 98% ee. The ¹H-NMR and IR spectral data of this productwas identical with those of the compound obtained in Example 7.

EXAMPLE 35 (2S)-2-(2,3,4-trifluoroanilino)propionic acid

Methyl 2-(2,3,4-trifluoroanilino)propionate (2.0 g) was suspended in a0.1 M phosphate buffer solution (pH 6.5; 400 ml). After adding ProteaseN (manufactured by Amano Seiyaku, originating in a bacterium belongingto the genus Bacillus; 0.4 g), the mixture was gently stirred. Themixture was further stirred for 14 hours while maintaining at 30° C.After adding methylene chloride, the liquid reaction mixture wasfiltered through celite to eliminate denatured protein and thenseparated. The organic layer was washed with a 5% aqueous solution ofsodium hydrogencarbonate and a saturated aqueous solution of sodiumchloride and then dried over anhydrous magnesium sulfate. Next, thesolvent was evaporated under reduced pressure to thereby give methyl(2R)-2-(2,3,4-trifluoroanilino)propionate (0.94 g). The optical purityof this product was 98% ee. On the other hand, the all aqueous layersobtained by the separation were combined and adjusted to pH 2 with 10%hydrochloric acid followed by extraction with IPE. The organic layer wasdried over anhydrous magnesium sulfate and evaporated. Thus, the titlecompound was obtained as a crude product (0.96 g). The optical purity ofthis product was 96% ee. Further, the crude product was recrystallizedfrom a solvent mixture of isopropyl ether with hexane. Thus, the titlecompound of 100% ee was obtained. The ¹H-NMR and IR spectral data ofthis product was identical with those of the compound obtained inExample 28.

EXAMPLE 36 (2R)-2-(2,3,4-trifluoroanilino)propionic acid

Methyl 2-(2,3,4-trifluoroanilino)propionate (1.0 g) was suspended in a0.1 M phosphate buffer solution (pH 6.5; 200 ml). After addingα-chymotrypsin (manufactured by Sigma; 0.2 g), the mixture was gentlystirred. The mixture was further stirred for 16 hours while maintainingat 30° C. After adding methylene chloride, the liquid reaction mixturewas filtered through celite to eliminate denatured protein and thenseparated. The organic layer was washed with a 5% aqueous solution ofsodium hydrogencarbonate and a saturated aqueous solution of sodiumchloride and then dried over anhydrous magnesium sulfate. Next, thesolvent was evaporated under reduced pressure to thereby give methyl(2S)-2-(2,3,4-trifluoroanilino)propionate (0.43 g). The optical purityof this product was 98% ee. On the other hand, the all aqueous layersobtained by the separation were combined and adjusted to pH 2 with 10%hydrochloric acid followed by extraction with IPE. The organic layer wasdried over anhydrous magnesium sulfate and evaporated. Thus, the titlecompound was obtained as a crude product (0.47 g). The optical purity ofthis product was 92% ee. Further, the crude product was recrystallizedfrom a solvent mixture of isopropyl ether with hexane. Thus, the titlecompound of 100% ee was obtained. The ¹H-NMR and IR spectral data ofthis product was identical those of the compound obtained in Example 29.

EXAMPLES 37 to 42

Reactions were performed as in Example 36 but using various substratesand catalysts (enzymes and microorganism) subjected to the asymmetrichydrolysis reaction.

TABLE Optical purity e.e. (%) Sub- Reaction Carboxylic Ex. strate EnzymeOrigin rate (%) acid Ester 19 Methyl Protease Rhizopus 47 92 (S) 96 (R)ester sp. 20 Methyl Protease Strepto- 53 88 (S) 97 (R) ester myces sp.21 Ethyl Protease Bacillus 46 93 (S) 99 (R) ester N sp. 22 Ethylα-Chymo- Bovine 48 86 (R) 96 (S) ester trypsin pancreas 23 EthylProtease Rhizopus 52 90 (S) 98 (R) ester sp. 24 Ethyl Protease Strepto-48 91 (S) 97 (R) ester myces sp.

EXAMPLE 43 (2S)-2-(2,3,4-Trifluoroanilino)propionic acid

Microbial cells (IAM-1623; Bacillus subtilis) were cultured in abouillon medium (pH 7.0; 50 ml) at 30° C. for 14 hours. After removingthe medium by centrifugation from the culture thus obtained, the cellsare freeze-dried to give freeze-dried cells. Methyl2-(2,3,4-trifluoroanilino)propionate (2.0 g) was suspended in a 0.1 Mphosphate buffer solution (pH 6.5; 100 ml). Then the above-describedfreeze-dried microbial cells (0.2 g) were added thereto and gentlystirred. The mixture was stirred for additional 6 hours whilemaintaining at 30° C. After adding methylene chloride, the liquidreaction mixture was filtered through celite to thereby eliminatedenatured protein and then separated. The organic layer was washed witha 5% aqueous solution of sodium hydrogencarbonate and a saturatedaqueous solution of sodium chloride and dried over anhydrous magnesiumsulfate. Then the solvent was evaporated under reduced pressure tothereby give methyl (2R)-2-(2,3,4-trifluoroanilino)propionic acid (0.92g). The optical purity of this product was 97% ee. On the other hand,all of the aqueous layers obtained by the separation were combined andadjusted to pH 2 with 10% hydrochloric acid followed by extraction withIPE. The organic layer was dried over anhydrous magnesium sulfate andevaporated to thereby give the title compound as 0.97 g of colorlesscrystals of a crude product. The optical purity of this product was 96%ee. Further, the crude product was recrystallized from a solvent mixtureof isopropyl ether with hexane. Thus, the title compound of 100% ee wasobtained. The ¹H-NMR and IR spectral data of this product was identicalwith those of the compound obtained in Example 28.

EXAMPLE 44 (2S)-2-(2,3,4-Trifluoroanilino)propionic acid

Microbial cells (IFO-1575; Zygoascus hellenicus) were cultured in an MYmedium (pH 6.0; 50 ml) at 30° C. for 48 hours. Methyl2-(2,3,4-trifluoroanilino)propionate (1.0 g) was suspended in a 0.1 Mphosphate buffer solution (pH 6.5; 90 ml). Then the above-describedliquid culture (10 ml) was added thereto and gently stirred. The mixturewas stirred for additional 16 hours while maintaining at 30° C. Then itwas treated as in Example 43 to thereby give methyl(2R)-2-(2,3,4-trifluoroanilino) propionate (0.39 g, optical purity 91%ee) and the title compound (0.45 g, optical purity 84% ee).

When the same asymmetric hydrolysis reaction as the one as describedabove was performed by using IFO8306: Nannizia gypsea as the microbialcells, the title compound was obtained at a reaction ratio of 55%(carboxylic acid 80% ee (S), ester 80% ee (R)).

Similarly, the title compound was obtained at a reaction ratio of 42%(carboxylic acid 92% ee (S), ester 60% ee (R)) by using IFO-12883:Actinomyces leporis. Also, the title compound was obtained at a reactionratio of 37% (carboxylic acid 91% ee (S), ester 50% ee (R)) by usingNRIC1271: Penicillium chrysogenum. The ¹H-NMR and IR spectral data ofeach product was identical with those of the compound obtained inExample 28.

EXAMPLE 45 Methyl 2-(2,3,4-trifluoroanilino)propionate

Methyl (2R)-2-(2,3,4-trifluoroanilino)propionate (100 mg, 38% ee) wasdissolved in toluene (2 ml) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU;71.8 mg) was added thereto at room temperature. Then the liquid reactionmixture was stirred at 110° C. for 16 hours. After adding hydrochloricacid (1 mol/l; 1 ml) to the liquid reaction mixture, the aqueous layerwas extracted with toluene. The organic layer was washed with water anda saturated aqueous solution of sodium chloride and dried over anhydrousmagnesium sulfate. After evaporating the solvent, the obtained residuewas subjected to silica gel column chromatography (ethyl acetate-normalhexane=1:4) to thereby give the title compound (86.8 mg) as colorlesscrystals. The optical purity of this product was 0% ee. The ¹H-NMR andIR spectral data of this product was identical with those of thecompound obtained in Example 5.

EXAMPLE 46 Methyl 2-(2,3,4-trifluoroanilino)propionate

Methyl (2R)-2-(2,3,4-trifluoroanilino)propionate (50 mg, 57% ee) wasdissolved in N,N-dimethylformamide (DMF; 1 ml) and potassium carbonate(63.2 mg) was added thereto at room temperature. Then the liquidreaction mixture was stirred at 110° C. for 19 hours. After adding waterto the liquid reaction mixture, the aqueous layer was extracted withethyl acetate. The organic layer was washed with water and dried overanhydrous magnesium sulfate. After evaporating the solvent, the obtainedresidue was subjected to silica gel column chromatography (ethylacetate-normal hexane=1:4) to thereby give the title compound (42.5 mg)as colorless crystals. The optical purity of this product was 0% ee. The¹H-NMR and IR spectral data of this product was identical with those ofthe compound obtained in Example 5.

EXAMPLE 47 Methyl 2-(2,3,4-trifluoroanilino)propionate

Methyl (2R)-2-(2,3,4-trifluoroanilino)propionate (200 mg, 57% ee) wasdissolved in dimethylacetamide (DMAc; 3 ml) and potassium carbonate(474.1 mg) was added thereto at room temperature. Then the liquidreaction mixture was stirred at 95° C. for 19 hours. After adding waterto the liquid reaction mixture, the aqueous layer was extracted withethyl acetate. The organic layer was washed with water and dried overanhydrous magnesium sulfate. After evaporating the solvent, the obtainedresidue was subjected to silica gel column chromatography (ethylacetate-normal hexane=1:4) to thereby give the title compound (179 mg)as colorless crystals. The optical purity of this product was 0% ee. The¹H-NMR and IR spectral data of this product was identical with those ofthe compound obtained in Example 5.

EXAMPLE 48 2-(2,3,4-Trifluoroanilino)propionic acid

Potassium tertiary-butoxide (123.4 mg) was suspended in DMAc (2 ml).Under ice-cooling, a solution of methyl(2R)-2-(2,3,4-trifluoroanilino)propionate (223 mg, 91% ee) in DMAc (2ml) was added thereto. The liquid reaction mixture was stirred at thesame temperature for 1 hour. Then an aqueous solution of sodiumhydroxide (3 mol/l; 2 ml) was added and the mixture was stirred for 1hour. The liquid reaction mixture was adjusted to pH 2 with an aqueoussolution of hydrochloric acid (3 mol/l) and then extracted with IPE. Theorganic layer was dried over anhydrous magnesium sulfate and evaporated.The crude product thus obtained was recrystallized from a solventmixture of methylene chloride with normal hexane to thereby give thetitle compound (206 mg) as colorless crystals. The optical purity ofthis product was 0% ee. Various spectral data of this product wasidentical with those obtained in Example 23.

EXAMPLE 49 2-(2,3,4-Trifluoroanilino)propionic acid

Methyl (2R)-2-(2,3,4-trifluoroanilino)propionate (223 mg, 91% ee) wasdissolved in DMAc (3 ml) and potassium carbonate (474.1 mg) was addedthereto at room temperature. The liquid reaction mixture was stirred at95° C. for 19 hours. After adding an aqueous solution of sodiumhydroxide (3 mol/l), the liquid reaction mixture was stirred for 1 hourand then adjusted to pH 2 with hydrochloric acid (3 mol/l) followed byextraction with IPE. Next, it was dried over anhydrous magnesiumsulfate. After evaporating the solvent, the crude product thus obtainedwas recrystallized from a solvent mixture of methylene chloride withnormal hexane to thereby give the title compound (198 mg) as colorlesscrystals. The optical purity of this product was 0% ee. Various spectraldata of this product was identical with those obtained in Example 23.

EXAMPLE 50 2-(2,3,4-Trifluoroanilino)propionic acid

Potassium carbonate (1.66 g) was suspended in DMAc (18 ml). Then, asolution (5 ml) of methyl (2R)-2-(2,3,4-trifluoroanilino) propionate(2.33 g, 54% ee) in DMAc was added dropped thereinto. The liquidreaction mixture was stirred at the same temperature for 2 hours. Thenan aqueous solution of potassium hydroxide (3 mol/l; 2 ml) was added andthe mixture was stirred for 15 minutes. The liquid reaction mixture wasadjusted to pH 2 with hydrochloric acid (6 mol/l), then extracted withmethyl t-butyl ether and dried over anhydrous magnesium sulfate. Afterevaporating the solvent, the crude product thus obtained was dissolvedin ethyl acetate (12 ml) and dropped into a solution (10 ml) ofcyclohexylamine (991.8 mg) in ethyl acetate at 60° C. over 30 minutes.Then the liquid reaction mixture was stirred at the same temperature for2 hours and the 2-(2,3,4-trifluoroanilino)propionic acid cyclohexylaminesalt (2.74 g) thus precipitated was collected by filtration.

The data of the 2-(2,3,4-trifluoroanilino)propionic acid-cyclohexylaminesalt are as follows.

Elemental analysis as C₁₅H₂₁F₃N₂O₂

Calculated (%): C, 56.59; H, 6.65; N, 8.80. Found (%): C, 56.52; H,6.67; N, 8.77.

¹H-NMR (270 MHz, CDCl₃) δ (ppm): 1.11–2.05 (m, 16H), 2.90–3.13 (m, 1H),3.73–3.86 (m, 1H), 6.30–6.47 (m, 1H), 6.75–6.89 (m, 1H)

Subsequently, hydrochloric acid (6 mol/l) was added to thiscyclohexylamine salt and the mixture was extracted with methyl t-butylether (MTBE) and dried over anhydrous magnesium sulfate. Afterevaporating the solvent, the title compound (1.92 g) was obtained ascolorless crystals. Its optical purity was 0% ee.

EXAMPLE 51 (2S)-2-(2,3,4-Trifluoroanilino)-1-propanol

Under ice-cooling, sodium borohydride (1.2 g) was dissolved in IPA (50ml). After adding methanol (5 ml), a solution of the compound (5.0 g)obtained in Example 1 in IPA was dropped thereinto. Then the liquidreaction mixture was heated to 50° C. and stirred for 1 hour. Next,hydrochloric acid (1 mol/l) was added and the mixture was stirred for awhile. Then a saturated aqueous solution of sodium hydrogencarbonate wasadded and the mixture was extracted with ethyl acetate. The extract waswashed with water, dried over anhydrous magnesium sulfate and filtered.After evaporating the solvent, the obtained residue was subjected tosilica gel column chromatography to give 3.7 g (84%) of the titlecompound as an oily substance.

¹H-NMR (CDCl₃, 270 MHz,) δ: 1.21 (d, J=6.3 Hz, 3H), 1.77 (brs, 1H),3.55–3.71 (m, 4H), 6.39–6.48 (m, 1H), 6.75–6.87 (m, 1H)

IR: 3394, 2967, 2933 cm⁻¹

MS; m/z:205 (M⁺)

EXAMPLE 52 (2S)-2-(2,3,4-Trifluoroanilino)propanol

At room temperature, sodium borohydride (35.7 mg) was suspended intoluene (0.2 ml). Then a solution (0.8 ml) of methyl(2S)-2-(2,3,4-trifluoroanilino)propionate (200 mg, 99.8% ee) in toluenewas added to the solution. After adding methanol (137.4 mg), the liquidreaction mixture was stirred for 6 hours. Then water was added to theliquid reaction mixture followed by extraction with ethyl acetate. Theorganic layer was washed with water and a saturated aqueous solution ofammonium chloride and dried over anhydrous magnesium sulfate. Afterevaporating the solvent, the obtained residue was subjected to silicagel column chromatography to thereby give 162.9 mg (99.8% ee) of thetitle compound as an oily substance. The ¹H-NMR and IR spectral data ofthis product was identical with those of the compound obtained inExample 51.

EXAMPLE 53 (2S)-2-(2,3,4-Trifluoroanilino)propanol

At room temperature, sodium borohydride (35.7 mg) was suspended inchlorobenzene (0.2 ml). Then a solution (0.8 ml) of methyl(2S)-2-(2,3,4-trifluoroanilino)propionate (200 mg, 99.8% ee) inchlorobenzene was added to the solution. After adding methanol (137.4mg), the liquid reaction mixture was stirred for 6 hours. Then water wasadded to the liquid reaction mixture followed by extraction withethylacetate. The organic layer was washed with water and a saturatedaqueous solution of ammonium chloride and dried over anhydrous magnesiumsulfate. After evaporating the solvent, the obtained residue wassubjected to silica gel column chromatography to thereby give 162.9 mg(99.8% ee) of the title compound as an oily substance. The ¹H-NMR and IRspectral data of this product was identical with those of the compoundobtained in Example 51.

EXAMPLE 54 (2S)-2-(2,3,4-Trifluoroanilino)propanol

At room temperature, sodium borohydride (35.7 mg) was suspended inhexane (0.2 ml). Then a solution (0.8 ml) of methyl(2S)-2-(2,3,4-trifluoroanilino)propionate (200 mg, 99.8% ee) in hexanewas added to the solution. After adding methanol (137.4 mg), the liquidreaction mixture was stirred for 1 hour. Then water was added to theliquid reaction mixture followed by extraction with ethyl acetate. Theorganic layer was washed with water and a saturated aqueous solution ofammonium chloride and dried over anhydrous magnesium sulfate. Afterevaporating the solvent, the obtained residue was subjected to silicagel column chromatography to thereby give 176 mg (99.8% ee) of the titlecompound as an oily substance. The ¹H-NMR and IR spectral data of thisproduct was identical with those of the compound obtained in Example 51.

EXAMPLE 55 (2S)-2-(2,3,4-Trifluoroanilino)propanol

At room temperature, sodium borohydride (35.7 mg) was suspended incyclohexane (0.2 ml). Then a solution (0.8 ml) of methyl(2S)-2-(2,3,4-trifluoroanilino)propionate (200 mg, 99.8% ee) incyclohexane was added to the solution. After adding methanol (137.4 mg),the liquid reaction mixture was stirred for 6 hours. Then water wasadded to the liquid reaction mixture followed by extraction with ethylacetate. The organic layer was washed with water and a saturated aqueoussolution of ammonium chloride and dried over anhydrous magnesiumsulfate. After evaporating the solvent, the obtained residue wassubjected to silica gel column chromatography to thereby give 176 mg(99.8% ee) of the title compound as an oily substance. The ¹H-NMR and IRspectral data of this product was identical with those of the compoundobtained in Example 51.

EXAMPLE 56 (2S)-2-(2,3,4-Trifluoroanilino)propanol

At room temperature, sodium borohydride (35.7 mg) was suspended in IPE(0.2 ml). Then a solution (0.8 ml) of methyl(2S)-2-(2,3,4-trifluoroanilino)propionate (200 mg, 99.8% ee) in IPE wasadded to the solution. After adding methanol (137.4 mg), the liquidreaction mixture was stirred for 2 hours. Then water was added to theliquid reaction mixture followed by extraction with ethyl acetate. Theorganic layer was washed with water and a saturated aqueous solution ofammonium chloride and dried over anhydrous magnesium sulfate. Afterevaporating the solvent, the obtained residue was subjected to silicagel column chromatography to thereby give 176 mg (99.8% ee) of the titlecompound as an oily substance. The ¹H-NMR and IR spectral data of thisproduct was identical with those of the compound obtained in Example 51.

EXAMPLE 57 (2S)-2-(2,3,4-Trifluoroanilino)propanol

At room temperature, sodium borohydride (35.7 mg) was suspended inmethyl t-butyl ether (0.2 ml). Then a solution (0.8 ml) of methyl(2S)-2-(2,3,4-trifluoroanilino)propionate (200 mg, 99.8% ee) in methylt-butyl ether was added to the solution. After adding methanol (137.4mg), the liquid reaction mixture was stirred for 1 hour. Then water wasadded to the liquid reaction mixture followed by extraction with ethylacetate. The organic layer was washed with water and a saturated aqueoussolution of ammonium chloride and dried over anhydrous magnesiumsulfate. After evaporating the solvent, the obtained residue wassubjected to silica gel column chromatography to thereby give 176 mg(99.8% ee) of the title compound as an oily substance. The ¹H-NMR and IRspectral data of this product was identical with those of the compoundobtained in Example 51.

EXAMPLE 58 (2S)-2-(2,3,4-Trifluoroanilino)propanol

At room temperature, sodium borohydride (35.7 mg) was suspended in THF(0.2 ml). Then a solution (0.8 ml) of methyl(2S)-2-(2,3,4-trifluoroanilino)propionate (200 mg, 99.8% ee) in THF wasadded to the solution. After adding methanol (137.4 mg), the liquidreaction mixture was stirred for 1 hour. Then water was added to theliquid reaction mixture followed by extraction with ethyl acetate. Theorganic layer was washed with water and a saturated aqueous solution ofammonium chloride and dried over anhydrous magnesium sulfate. Afterevaporating the solvent, the obtained residue was subjected to silicagel column chromatography to thereby give 176 mg (99.8% ee) of the titlecompound as an oily substance. The ¹H-NMR and IR spectral data of thisproduct was identical with those of the compound obtained in Example 51.

EXAMPLE 59 (2S)-2-(2,3,4-Trifluoroanilino)propanol

At room temperature, sodium borohydride (35.7 mg) was suspended in1,2-dimethoxyethane (0.2 ml). Then a solution (0.8 ml) of methyl(2S)-2-(2,3,4-trifluoroanilino)propionate (200 mg, 99.8% ee) in DME wasadded to the solution. After adding methanol (137.4 mg), the liquidreaction mixture was stirred for 1 hour. Then water was added to theliquid reaction mixture followed by extraction with ethyl acetate. Theorganic layer was washed with water and a saturated aqueous solution ofammonium chloride and dried over anhydrous magnesium sulfate. Afterevaporating the solvent, the obtained residue was subjected to silicagel column chromatography to thereby give 176 mg (99.8% ee) of the titlecompound as an oily substance. The ¹H-NMR and IR spectral data of thisproduct was identical with those of the compound obtained in Example 51.

EXAMPLE 60 (2S)-2-(2,3,4-Trifluoroanilino)propanol

At room temperature, sodium borohydride (35.7 mg) was suspended inchloroform (0.2 ml). Then a solution (0.8 ml) of methyl(2S)-2-(2,3,4-trifluoroanilino)propionate (200 mg, 99.8% ee) inchloroform was added to the solution. After adding methanol (137.4 mg),the liquid reaction mixture was stirred for 6 hours. Then water wasadded to the liquid reaction mixture followed by extraction with ethylacetate. The organic layer was washed with water and a saturated aqueoussolution of ammonium chloride and dried over anhydrous magnesiumsulfate. After evaporating the solvent, the obtained residue wassubjected to silica gel column chromatography to thereby give 137.3 mg(99.8% ee) of the title compound as an oily substance. The ¹H-NMR and IRspectral data of this product was identical with those of the compoundobtained in Example 51.

EXAMPLE 61 (2S)-2-(2,3,4-Trifluoroanilino)propanol

At room temperature, sodium borohydride (35.7 mg) was suspended inmethylene chloride (0.2 ml). Then a solution (0.8 ml) of methyl.(2S)-2-(2,3,4-trifluoroanilino)propionate (200 mg, 99.8% ee) in metylenechloride was added to the solution. After adding methanol (137.4 mg),the liquid reaction mixture was stirred for 1 hour. Then water was addedto the liquid reaction mixture followed by extraction with ethylacetate. The organic layer was washed with water and a saturated aqueoussolution of ammonium chloride and dried over anhydrous magnesiumsulfate. After evaporating the solvent, the obtained residue wassubjected to silica gel column chromatography to thereby give 159.8 mg(99.8% ee) of the title compound as an oily substance. The ¹H-NMR and IRspectral data of this product was identical with those of the compoundobtained in Example 51.

EXAMPLE 62 (2S)-2-(2,3,4-Trifluoroanilino)propanol

At room temperature, sodium borohydride (35.7 mg) was suspended in1,2-dichloroethane (EDC, 0.2 ml). Then a solution (0.8 ml) of methyl(2S)-2-(2,3,4-trifluoroanilino)propionate (200 mg, 99.8% ee) in EDC wasadded to the solution. After adding methanol (137.4 mg), the liquidreaction mixture was stirred for 1 hour. Then water was added to theliquid reaction mixture followed by extraction with ethyl acetate. Theorganic layer was washed with water and a saturated aqueous solution ofammonium chloride and dried over anhydrous magnesium sulfate. Afterevaporating the solvent, the obtained residue was subjected to silicagel column chromatography to thereby give 159.8 mg (99.8% ee) of thetitle compound as an oily substance. The ¹H-NMR and IR spectral data ofthis product was identical with those of the compound obtained inExample 51.

EXAMPLE 63 Diethyl[2,3,4-trifluoro[(1S)-2-hydroxy-1-methylethyl]anilino]methylenemalonate

The compound (300 mg) obtained in Example 51, diethylethoxymethylenemalonate (632 mg) and tetrahexylammonium chloride (57 mg)were dissolved in acetone (3 ml). After adding potassium carbonate (445mg), the mixture was stirred at room temperature for 4.5 hours. Afterthe completion of the reaction, the solvent was evaporated. Then theresidue thus obtained was subjected to silica gel column chromatographyto thereby give 338 mg (84%) of the title compound as a colorless solid.

¹H-NMR (CDCl₃, 270 MHz) δ: 1.13 (t, J=7.26 Hz, 3H), 1.23 (t, J=7.26 Hz,3H), 2.34 (brs, 1H), 3.62–3.81 (m, 5H), 4.16 (q, J=7.26, 2H), 6.87–7.11(m, 2H), 7.70 (s, 1H)

IR (KBr): 3451, 3093, 2989, 1706, 1678 cm⁻¹

MS; m/z: 375 (M⁺)

EXAMPLE 64 Diethyl[2,3,4-trifluoro[(1S)-2-hydroxy-1-methylethyl]anilino]methylenemalonate

The compound (103 mg) obtained in Example 51, diethylethoxymethylenemalonate (108 mg) and tetrahexylammonium chloride (29 mg)were dissolved in dichloromethane (1 ml). After adding potassiumcarbonate (138 mg), the mixture was stirred at room temperature for 22hours. After the completion of the reaction, the residue was filteredoff and the solvent was evaporated. Then the residue thus obtained wassubjected to silica gel column chromatography to thereby give 147 mg(78%) of the title compound as a colorless solid. The ¹H-NMR and IRspectral data of this product was identical with those of the compoundobtained in Example 63.

EXAMPLE 65 Diethyl[2,3,4-trifluoro[(1S)-2-hydroxy-1-methylethyl]anilino]methylenemalonate

Potassium tertiary-butoxide (62 mg) was added to DMF (2 ml) and cooledto 0° C. Then a solution of the compound (100 mg) obtained in Example 51in DMF (200 μl) was dropped thereinto. After stirring for 15 minutes,diethyl ethoxymethylenemalonate was dropped thereinto and the resultantmixture was stirred for 8 hours at room temperature. After treating in aconventional manner, it was subjected to silica gel columnchromatography to thereby give 137 mg (75%) of the title compound as acolorless solid. The ¹H-NMR and IR spectral data of this product wasidentical with those of the compound obtained in Example 63.

EXAMPLE 66 Diethyl[2,3,4-trifluoro[(1S)-2-hydroxy-1-methylethyl]anilino]methylenemalonate

To the compound (103 mg) obtained in Example 51 was added diethylethoxymethylenemalonate (127 mg). Then the obtained mixture was stirredfor 1 hour while heating to 100° C. under atmospheric pressure. Further,it was stirred at the same temperature for 1.5 hour under reducedpressure and then under atmospheric pressure for additional 16 hours. Byanalyzing reversed phase HPLC with the use of the compound of Example 63as a specimen, the obtained product corresponded to 142 mg (78%) of thetitle compound.

EXAMPLE 67 Diethyl[2,3,4-trifluoro[(1S)-2-hydroxy-1-methylethyl]anilino]methylenemalonate

The compound (103 mg) obtained in Example 51 and dimethylethoxymethylenemalonate (87 mg) were dissolved in toluene (3 ml) and themixture was heated under reflux for 21 hours. Then the residue wasfiltered off and the solvent was evaporated. The obtained residue wassubjected to silica gel column chromatography to give 125 mg (72%) ofthe title compound as colorless crystals.

¹H-NMR (CDCl₃, 270 MHz) δ: 1.22–1.25 (m, 3H), 3.27 (s, 1H), 3.57–3.82(m, 8H), 6.96–7.10 (m, 2H), 7.76 (s, 1H)

IR (KBr): 3452, 2954, 1722 cm⁻¹

MS; m/z: 347 (M⁺), 316, 284

EXAMPLE 68 Diethyl[2,3,4-trifluoro[(1S)-2-hydroxy-1-methylethyl]anilino]methylenemalonate

At room temperature, potassium hydroxide (330 mg) and tetrahexylammoniumchloride (190.1 mg) were dissolved in DMF (15 ml). After adding asolution (5 ml) of (2S)-2-(2,3,4-trifluoroanilino)propanol (1 g, 99.8%ee) and diethyl ethoxymethylenemalonate (2.09 g) in DMF, the resultantmixture was stirred for 1 hour. After adding water, the liquid reactionmixture was extracted with a solvent mixture of ethyl acetate andn-hexane (3:2). The organic layer was washed with water and dried overanhydrous magnesium sulfate. After evaporating the solvent, IPE wasadded to the obtained residue and the mixture was stirred at 0° C. for 1hour. The crystals thus precipitated were collected by filtration andthe moist product thus obtained was dried under reduced pressure. Thus,the title compound (1.65 g, 99.8% ee) was obtained as colorlesscrystals. The H-NMR and IR spectral data of this product was identicalwith those of the compound obtained in Example 63.

EXAMPLE 69 Diethyl[2,3,4-trifluoro[(1S)-2-hydroxy-1-methylethyl]anilino]methylenemalonate

At room temperature, potassium hydroxide (330 mg) and tetrabutylammoniumhydrogensulfate (82.7 mg) were dissolved in DMF (15 ml). After adding asolution (5 ml) of (2S)-2-(2,3,4-trifluoroanilino)propanol (1 g, 99.8%ee) and diethyl ethoxymethylenemalonate (2.09 g) in DMF, the resultantmixture was stirred for 1 hour. After adding water, the liquid reactionmixture was extracted with a solvent mixture of ethyl acetate andn-hexane (3:2). The organic layer was washed with water and dried overanhydrous magnesium sulfate. After evaporating the solvent, IPE wasadded to the obtained residue and the mixture was stirred at 0° C. for 1hour. The crystals thus precipitated were collected by filtration andthe moist product thus obtained was dried under reduced pressure. Thus,the title compound (1.7 g, 99.8% ee) was obtained as colorless crystals.The ¹H-NMR and IR spectral data of this product was identical with thoseof the compound obtained in Example 63.

EXAMPLE 70 Diethyl[2,3,4-trifluoro[(1S)-2-hydroxy-1-methylethyl]anilino]methylenemalonate

At room temperature, potassium hydroxide (330 mg) and tetrabutylammoniumhydrogensulfate (82.7 mg) were dissolved in DMF (15 ml). After adding asolution (5 ml) of (2S)-2-(2,3,4-trifluoroanilino)propanol (1 g, 99.8%ee) and diethyl ethoxymethylenemalonate (2.09 g) in DMF, the resultantmixture was stirred for 1 hour. After adding water, the liquid reactionmixture was extracted with a solvent mixture of ethyl acetate andn-hexane (3:2). The organic layer was washed with water and dried overanhydrous magnesium sulfate. After evaporating the solvent, IPE wasadded to the obtained residue and the mixture was stirred at 0° C. for 1hour. The crystals thus precipitated were collected by filtration andthe moist product thus obtained was dried under reduced pressure. Thus,the title compound (1.65 g, 99.8% ee), was obtained as colorlesscrystals. The ¹H-NMR and IR spectral data of this product was identicalwith those of the compound obtained in Example 63.

EXAMPLE 71 Diethyl[(3S)-7,8-difluoro-3-methyl-2,3-dihydro-4H-[1,4]benzoxazin-4-yl]methylenemalonate

To DMF (5 ml) was added potassium tertiary-butoxide (74 mg) underice-cooling. After dropping a solution of the compound (200 mg) obtainedin Example 63 in DMF (1 ml), the resultant mixture was stirred at 60° C.for 18 hours. After treating in a conventional manner, the obtainedresidue was subjected to silica gel column chromatography to therebygive 149 mg (79%) of the title compound. The physical constants of theobtained compounds was identical with those described in Japanese PatentNo. 2,769,174.

EXAMPLE 72 Diethyl[(3S)-7,8-difluoro-3-methyl-2,3-dihydro-4H-[1,4]benzoxazin-4-yl]methylenemalonate

To DMF (2 ml) was added potassium tertiary-butoxide (226 mg) underice-cooling. After dropping a solution of the compound (100 mg) obtainedin Example 51 and diethyl ethoxymethylenemalonate (293 mg) in DMF (0.5ml), the resultant mixture was stirred at room temperature for 18 hours.After treating in a conventional manner, the obtained residue wassubjected to silica gel column chromatography to thereby give 113 mg(65%) of the title compound. The physical constants of the obtainedcompounds was identical with those described in Japanese Patent No.2,769,174.

EXAMPLE 73 Diethyl[(3S)-7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazin-4-yl]methylenemalonate

Potassium hydroxide (180 mg) and tetrabutylammonium hydrogensulfate(90.4 mg) were dissolved in DMF (15 ml) by heating to 60° C. and asolution of diethyl[2,3,4-trifluoro[(1S)-2-hydroxy-1-methylethyl]anilino]methylenemalonate(1 g, 99.8% ee) and diethyl ethoxymethylenemalonate (120 mg) in DMF 85ml) was added thereto. The obtained mixture was stirred at the sametemperature for 2 hours. After adding water, the liquid reaction mixturewas extracted with ethyl acetate. The organic layer was dried overanhydrous magnesium sulfate. After evaporating the solvent, the obtainedresidue was subjected to silica gel column chromatography. Thus, 852 mg(99.8% ee) of the title compound was obtained as a yellow oilysubstance. Various spectral data was identical with those described inJapanese Patent No. 2,769,174.

EXAMPLE 74 Diethyl[(3S)-7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazin-4-yl]methylenemalonate

Potassium hydroxide (180 mg) and benzyl trimethylammonium chloride (49.5mg) were dissolved in DMF (15 ml) by heating to 70° C. and a solution ofdiethyl[2,3,4-trifluoro[(1S)-2-hydroxy-1-methylethyl]anilino]methylenemalonate(1 g, 99.8% ee) and diethyl ethoxymethylenemalonate (120 mg) in DMF (5ml) was added thereto. The obtained mixture was stirred at the sametemperature for 4 hours. After adding water, the liquid reaction mixturewas extracted with ethyl acetate. The organic layer was dried overanhydrous magnesium sulfate. After evaporating the solvent, the obtainedresidue was subjected to silica gel column chromatography. Thus, 871 mg(99.8% ee) of the title compound was obtained as a yellow oilysubstance. Various spectral data was identical with those described inJapanese Patent No. 2,769,174.

EXAMPLE 75 Diethyl[(3S)-7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazin-4-yl]methylenemalonate

Potassium hydroxide (180 mg) and benzyl trimethylammonium chloride (60.7mg) were dissolved in DMF (15 ml) by heating to 60° C. and a solution (5ml) of diethyl[2,3,4-trifluoro[(1S)-2-hydroxy-1-methylethyl]anilino]methylenemalonate(1 g, 99.8% ee) and diethyl ethoxymethylenemalonate (120 mg) in DMF wasadded thereto. The obtained mixture was stirred at the same temperaturefor 7 hours. After adding water, the liquid reaction mixture wasextracted with ethyl acetate. The organic layer was dried over anhydrousmagnesium sulfate. After evaporating the solvent, the obtained residuewas subjected to silica gel column chromatography. Thus, 899 mg (99.8%ee) of the title compound was obtained as a yellow oily substance.Various spectral data was identical with those described in JapanesePatent No. 2,769,174.

EXAMPLE 76 Diethyl[(3S)-7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazin-4-yl]methylenemalonate

At room temperature, KOH (330 mg) and tetrahexylammonium chloride (190.1mg) were dissolved in DMF (15 ml). After adding a solution (5 ml) of(2S)-2-(2,3,4-trifluoroanilino)propanol (1 g, 99.8% ee) and diethylethoxymethylenemalonate (2.09 g) in DMF, the mixture was stirred for 1hour. Next, it was heated to 60° C. and a solution (5 ml) of KOH (330mg) and diethyl ethoxymethylenemalonate (120 mg) in DMF was addedthereto. The resultant mixture was stirred at the same temperature for 5hours. After adding water, the liquid reaction mixture was extractedwith ethyl acetate. The organic layer was dried over anhydrous magnesiumsulfate. After evaporating the solvent, the obtained residue wassubjected to silica gel column chromatography. Thus, 1.37 g (99.8% ee)of the title compound was obtained as a yellow oily substance. Variousspectral data was identical with those described in Japanese Patent No.2,769,174.

EXAMPLE 77 Diethyl[(3S)-7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazin-4-yl]methylenemalonate

At room temperature, KOH (330 mg) and tetrabutylammonium hydrogensulfate(82.7 mg) were dissolved in DMF (15 ml). After adding a solution (5 ml)of (2S)-2-(2,3,4-trifluoroanilino)propanol (1 g, 99.8% ee) and diethylethoxymethylenemalonate (2.09 g) in DMF, the mixture was stirred for 1hour. Next, it was heated to 60° C. and a solution (5 ml) of KOH (330mg) and diethyl ethoxymethylenemalonate (120 mg) in DMF was addedthereto. The resultant mixture was stirred at the same temperature for 5hours. After adding water, the liquid reaction mixture was extractedwith ethyl acetate. The organic layer was dried over anhydrous magnesiumsulfate. After evaporating the solvent, the obtained residue wassubjected to silica gel column chromatography. Thus, 1.3 g (99.8% ee) ofthe title compound was obtained as a yellow oily substance. Variousspectral data was identical with those described in Japanese Patent No.2,769,174.

EXAMPLE 78(3S)-(+)-7,8-Difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine

To DMF (2 ml) was added sodium hydride (39 mg) and the mixture washeated to 60° C. in an oil bath. Next, a solution of the compound (100mg) obtained in Example 51 in DMF was dropped there into and theobtained mixture was stirred for 1 hour. After treating in aconventional manner, the mixture was subjected to silica gel columnchromatography to give 60 mg (66%) of the title compound. The opticalpurity determined by HPCL was >94% ee. Various spectral data wasidentical with those of a specimen synthesized separately.

EXAMPLE 79(3S)-(+)-7,8-Difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine

To DMF (2 ml) was added potassium tertiary-butoxide (110 mg) underice-cooling. Next, a solution of the compound (100 mg) obtained inExample 51 in DMF was dropped thereinto and the obtained mixture wasstirred for 30 minutes. After treating in a conventional manner, themixture was subjected to silica gel column chromatography to give 72 mg(79%) of the title compound. The optical purity determined by HPCLwas >94% ee. Various spectral data was identical with those of aspecimen synthesized separately.

EXAMPLE 80(3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine•p-toluenesulfonate

To sodium tertiary-butoxide (t-BuONa; 748 mg) was added DMAc (8 ml).After dissolving by heating at 80° C., a solution of(2S)-2-(2,3,4-trifluoroanilino)propanol (1.0 g; 99.8% ee) in DMAc (2 ml)was added thereto at the same temperature. After stirring for 30 minutesand cooling by allowing to stand, water (30 ml) was added at roomtemperature. The resultant mixture was extracted with ethyl acetate(AcOEt; 20 ml) thrice. The organic layer thus extracted was concentratedunder reduced pressure. The obtained solution was dropped into asolution of p-toluenesulfonic acid monohydrate (927.5 mg) in AcOEt (10ml). After stirring at room temperature for additional 1 hour, crystalswere collected by filtration while washing with AcOEt (7 ml). The moistproduct thus obtained was dried under reduced pressure to give the titlecompound (1.6 g) as colorless crystals.

¹H-NMR (CD₃OD) δ: 1.43 (d, 3H, J=5.7 Hz), 2.34 (d, 3H, J=12.2 Hz),3.85–3.89 (m, 1H), 4.09–4.17 (m, 1H), 7.22–7.32 (m, 1H), 6.77–6.89 (m,1H)

Melting point: 131 to 133° C. (decomposition)

Elemental analysis as C₁₆H₁₇NO₄S

Calculated (%): C, 53.77; H, 4.79; N, 3.92%. Found (%): C, 53.80; H,4.81; N, 3.86%.

EXAMPLE 81(3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine•p-toluenesulfonate

To potassium tertiary-butoxide (t-BuOK; 1.24 g) was added DMF (18 ml).After dissolving by heating at 80° C., a solution of(2S)-2-(2,3,4-trifluoroanilino)propanol (1.0 g; 99.8% ee) in DMF (2 ml)was added thereto at the same temperature. After stirring for 30 minutesand cooling by allowing to stand, water (40 ml) was added at roomtemperature. The resultant mixture was extracted with AcOEt (20 ml)thrice. The organic layer thus extracted was concentrated under reducedpressure. The obtained solution was dropped into a solution ofp-toluenesulfonic acid monohydrate (927.5 mg) in AcOEt (10 ml). Afterstirring at room temperature for additional 1 hour, crystals werecollected by filtration while washing with AcOEt (7 ml). The crystalsthus obtained were dried under reduced pressure to give the titlecompound (1.39 g) as colorless crystals. Various spectral data wasidentical with those obtained in Example 80.

EXAMPLE 82(3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine•p-toluenesulfonate

To sodium hydride (NaH; 262 mg) was added DMF (18 ml). After dissolvingby heating at 80° C., a solution of(2S)-2-(2,3,4-trifluoroanilino)propanol (1.0 g; 99.8% ee) in DMF (2 ml)was added thereto at the same temperature. After stirring for 30 minutesand cooling by allowing to stand, water (40 ml) was added at roomtemperature. The resultant mixture was extracted with AcOEt (20 ml)thrice. The organic layer thus extracted was concentrated under reducedpressure. The obtained solution was dropped into a solution ofp-toluenesulfonic acid monohydrate (927.5 mg) in AcOEt (10 ml). Afterstirring at room temperature for additional 1 hour, crystals werecollected by filtration while washing with AcOEt (7 ml). The crystalsthus obtained were dried under reduced pressure to give the titlecompound (1.14 g) as colorless crystals. Various spectral data wasidentical with those obtained in Example 80.

EXAMPLE 83 (3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine

(3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine•p-toluenesulfonate(1 g) was suspended in AcOEt (10 ml) and then an aqueous solution ofsodium hdyrogencarbonate (NaHCO₃; 10 ml) was added thereto. Afterstirring at room temperature for 1 hour, the mixture was extracted withAcOEt. The organic layer was dried over anhydrous magnesium sulfate andconcentrated under reduced pressure to thereby give the title compound(516 mg, 99.8% ee) as a yellow oily substance.

¹H-NMR (270 MHz, CDCl₃) δ: 2.16 (s, 3H), 4.60 (s, 2H), 6.28 (ddd, 1H,J=2.3, 4.7, 8.9 Hz), 6.50–6.80 (m, 1H)

EXAMPLE 84 (3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazinemethanesulfonate

To t-BuONa (748 mg) was added DMAc (8 ml). After dissolving by heatingto 80° C., a solution of (2S)-2-(2,3,4-trifluoroanilino)propanol (1.0 g,99.8% ee) in DMAc (2 ml) was added thereto at the same temperature.After stirring for 30 minutes and cooling by allowing to stand, water(30 ml) was added thereto at room temperature. The resultant mixture wasextracted with AcOEt (20 ml) thrice. The organic layers were combinedand concentrated under reduced pressure. The obtained solution was addedto a solution of methanesulfonic acid (468.4 mg) in AcOEt (5 ml). Afterstirring for additional 1 hour at room temperature, crystals werecollected by filtration while washing with AcOEt (5 ml). The moistproduct thus obtained was dried to give the title compound (960.4 mg) ascolorless crystals.

¹H-NMR (270 MHz, CD₃OD) δ: 1.45 (d, 3H, J=6.8 Hz), 2.68 (s, 3H),3.89–3.93 (m, 1H), 4.17 (dd, 1H, J=8.9, 12.2 Hz)), 4.57 (dd, 1H, J=2.7,11.9 Hz), 6.96–7.15 (m, 2H)

Melting point: 131 to 133° C. (decomposition)

Elemental analysis as C₁₀H₁₃F₂NO₄S

Calculated (%): C, 42.70; H, 4.66%; N, 4.98%. Found (%) C, 42.70; H,4.66%; N, 4.92%.

EXAMPLE 85 (3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazinemethanesulfonate

To t-BuOK (1.24 g) was added DMF (18 ml). After dissolving by heating at80° C., a solution of (2S)-2-(2,3,4-trifluoroanilino)propanol (1.0 g;99.8% ee) in DMF (2 ml) was added thereto at the same temperature. Afterstirring for 30 minutes and cooling by allowing to stand, water (30 ml)was added at room temperature. The resultant mixture was extracted withAcOEt (20 ml) thrice. The organic layers were combined and concentratedunder reduced pressure. The obtained solution was dropped into asolution of methanesulfonic acid (468.4 mg) in AcOEt (5 ml). Afterstirring at room temperature for additional 1 hour, crystals werecollected by filtration while washing with AcOEt (5 ml). The moistproduct thus obtained was dried under reduced pressure to give the titlecompound (875 mg) as colorless crystals. Various spectral data wasidentical with those obtained in Example 84.

EXAMPLE 86(3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine•methanesulfonate

To NaH (262 mg) was added DMF (18 ml). After dissolving by heating at80° C., a solution of (2S)-2-(2,3,4-trifluoroanilino)propanol (1.0 g;99.8% ee) in DMF (2 ml) was added thereto at the same temperature. Afterstirring for 30 minutes and cooling by allowing to stand, water (30 ml)was added at room temperature. The resultant mixture was extracted withAcOEt (20 ml) thrice. The organic layers were combined and concentratedunder reduced pressure. The obtained solution was dropped into asolution of methanesulfonic acid (468.4 mg) in AcOEt (5 ml). Afterstirring at room temperature for additional 1 hour, crystals werecollected by filtration while washing with AcOEt (5 ml). The moistproduct thus obtained was dried under reduced pressure to give the titlecompound (894 mg) as colorless crystals. Various spectral data wasidentical with those obtained in Example 84.

EXAMPLE 87 (3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine

(3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine•p-toluenesulfonate (1 g) was suspended in AcOEt (10 ml) and thenan aqueous solution of NaHCO₃ (10 ml) was added thereto. After stirringat room temperature for 1 hour, the mixture was extracted with AcOEt.The organic layer was dried over anhydrous magnesium sulfate andconcentrated under reduced pressure to thereby give the title compound(645.2 mg, 99.8% ee) as a yellow oily substance. Various spectral datawas identical with those obtained in Example 83.

EXAMPLE 88(3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine•(±)-camphorsulfonate

To t-BuONa (748 mg) was added DMAc (8 ml). After dissolving by heatingat 80° C., a solution of (2S)-2-(2,3,4-trifluoroanilino)propanol (1.0 g;99.8% ee) in DMAc (2 ml) was added thereto at the same temperature.After stirring for 30 minutes and cooling by allowing to stand, water(30 ml) was added at room temperature. The resultant mixture wasextracted with AcOEt (20 ml) thrice. The organic layers were combinedand concentrated under reduced pressure. The obtained solution wasdropped into a solution of (±)-camphorsulfonic acid (1.137 g) in 5% EtOH(ethanol)/AcOEt (7 ml). After stirring at room temperature foradditional 1 hour, crystals were collected by filtration while washingwith AcOEt (7 ml). The moist product thus obtained was dried underreduced pressure to give the title compound (1.8 g) as colorlesscrystals.

¹H-NMR (270 MHz, CD₃OD): 0.613 (s, 3H), 0.847 (s, 3H), 1.36–1.46 (m,1H), 1.45 (d, 3H, J=6.5 Hz), 1.55–1.65 (m, 1H), 1.88 (d, 1H, J=18.4 Hz),1.98–2.06 (m, 2H), 2.76 (d, 1H, J=14.6 Hz), 3.27 (d, 1H, J=14.6 Hz),3.85–3.97 (m, 1H), 4.18 (dd, 1H, J=8.6, 12.2 Hz), 4.57 (dd, 1H, J=2.7,11.9 Hz), 6.49–7.19 (m, 2H)

Melting point: 232 to 236° C. (decomposition)

Elemental analysis as C₁₉H₂₅NO₅S

Calculated (%): C, 54.66; H, 6.04; N, 3.36%. Found (%): C, 54.63; H,6.04; N, 3.29%.

EXAMPLE 89(3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine•(±)-camphorsulfonate

To t-BuOK (1.24 g) was added DMF (18 ml). After dissolving by heating at80° C., a solution of (2S)-2-(2,3,4-trifluoroanilino)propanol (1.0 g;99.8% ee) in DMF (2 ml) was added thereto at the same temperature. Afterstirring for 30 minutes and cooling by allowing to stand, water (30 ml)was added at room temperature. The resultant mixture was extracted withAcOEt (20 ml) thrice. The organic layers were combined and concentratedunder reduced pressure. The obtained solution was dropped into asolution of (±)-camphorsulfonic acid (1.137 g) in 5% EtOH/AcOEt (7 ml).After stirring at room temperature for additional 1 hour, crystals werecollected by filtration while washing with AcOEt (7 ml). The moistproduct thus obtained was dried under reduced pressure to give the titlecompound (1.72 g) as colorless crystals. Various spectral data wasidentical with those obtained in Example 88.

EXAMPLE 90 (3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine(O)-camphorsulfonate

To NaH (242 mg) was added DMF (18 ml). After dissolving by heating at80° C., a solution of (2S)-2-(2,3,4-trifluoroanilino)propanol (1.0 g;99.8% ee) in DMF (2 ml) was added thereto at the same temperature. Afterstirring for 30 minutes and cooling by allowing to stand, water (30 ml)was added at room temperature. The resultant mixture was extracted withAcOEt (20 ml) thrice. The organic layer thus extracted was concentratedunder reduced pressure. The obtained solution was dropped into asolution of (±)-camphorsulfonic acid (1.137 g) in 5% EtOH/AcOEt (7 ml).After stirring at room temperature for additional 1 hour, crystals werecollected by filtration while washing with AcOEt (7 ml). The moistproduct thus obtained was dried under reduced pressure to give the titlecompound (1.41 g) as colorless crystals. Various spectral data wasidentical with those obtained in Example 88.

EXAMPLE 91 (3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine

(3S)-7,8-Difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine•p-toluenesulfonate(1 g) was suspended in AcOEt (10 ml) and then an aqueous solution ofNaHCO₃ (10 ml) was added thereto. After stirring at room temperature for1 hour, the mixture was extracted with AcOEt. The organic layer wasdried over anhydrous magnesium sulfate and concentrated under reducedpressure to thereby give the title compound (438.9 mg, 99.8% ee) as ayellow oily substance. Various spectral data was identical with thoseobtained in Example 83.

EXAMPLE 92 Diethyl[(3S)-7,8-difluoro-3-methyl-2,3-dihydro-4H-[1,4]benzoxazin-4-yl]methylenemalonate

To DMF (2.5 ml) was added potassium tertiary-butoxide (75 mg) underice-cooling. After dropping a solution of the compound (100 mg) obtainedin Example 78 and diethyl ethoxymethylenemalonate (233 mg) in DMF (0.5ml), the resultant mixture was stirred for 2 hours. After treating in aconventional manner, the obtained residue was subjected to silica gelcolumn chromatography to thereby give 153 mg (88%) of the title compoundas an oily product. The physical constants of the obtained compounds wasidentical with those described in Japanese Patent No. 2,769,174.

EXAMPLE 93 Diethyl[(3S)-7,8-difluoro-3-methyl-2,3-dihydro-4H-[1,4]benzoxazin-4-yl]methylenemalonate

1.20 g (99.8% ee) of(3S)-7,8-difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazine was dissolvedin toluene (0.5 ml). After adding diethyl ethoxymethylenemalonate (1.92g), the mixture was stirred at 120 for 30 minutes and then at 140° C.under reduced pressure for 30 minutes. The residue was subjected tosilica gel column chromatography. Thus, 2.19 g (99.8% ee) of the titlecompound was obtained as a yellow oily product. The physical constantsof the obtained compounds was identical with those described in JapanesePatent No. 2,769,174.

EXAMPLE 94 2-(2,3,4-Trifluoroanilino)propyl 4-nitrobenzoate

2-Hydroxypropyl 4-nitrobenzoate (225 mg) was dissolved indichloromethane (1 ml) by stirring. At −50° C., a solution oftrifluoromethanesulfonic anhydride (339 mg) dissolved in dichloromethane(1 ml) was added thereto. After stirring at the same temperature for 30minutes, dichloromethane was evaporated under reduced pressure at 0° C.After dissolving the residue in dichloromethane (1 ml), a solution of2,3,4-trifluoroaniline (147.1 mg) dissolved in dichloromethane (1 ml)was dropped thereinto at 0° C. and the resultant mixture was stirred atthe same temperature for 30 minutes. Next, dichloromethane (10 ml) wasadded to the solution followed by washing with water (10 ml). Thedichloromethane layer was concentrated under reduced pressure and theobtained residue was separated and purified by silica gel columnchromatography to thereby give 159.4 mg (45%) of the title compound asyellow crystals.

¹H-NMR (270 MHz, CDCl₃) δ: 1.38 (d, 6.6 Hz, 3H), 3.76–3.92 (m, 2H), 4.30(dd, J=5.3, 11.2 Hz, 1H), 4.49 (dd, J=5.3, 11.2 Hz, 1H), 6.46–6.55 (m,1H), 6.77–6.88 (m, 1H), 8.17 (dd, J=2.0, 6.9 Hz, 2H), 8.29 (dd, J=2.0,6.9 Hz, 1H)

EXAMPLE 95 2-(2,3,4-Trifluoroanilino)propanol

2-(2,3,4-Trifluoroanililno)propyl 4-nitrobenzoate (50 mg) and potassiumhydroxide (11.8 mg) were added to methanol (2 ml) and dissolved bystirring. Then the mixture was stirred at room temperature for 18 hours.After evaporating methanol under reduced pressure, chloroform (5 ml) andwater (5 ml) were added and the resultant mixture was separated. Thechloroform layer was concentrated and purified by silica gel columnchromatography to thereby give 19.8 mg (69.1%) of the title compound asa colorless oily product.

¹H-NMR (270 MHz, CDCl₃) δ: 1.22 (d, J=5.9 Hz, 3H), 3.55–3.74 (m, 4H),6.3–6.5 (m, 1H), 6.76–6.87 (m, 1H).

EXAMPLE 96 2-Hydroxypropyl 4-nitrobenzoate

2-Hydroxypropanol (4.57 g) was dissolved in toluene (80 ml) by stirringand triethylamine (6.68 g) was dropped thereinto at 0° C. After stirringat the same temperature for 30 minutes, a solution of p-nitrobenzoylchloride (11.4 g) dissolved in toluene (12 ml) was slowly added thereto.The resultant mixture was heated to room temperature and stirred for 2hours. Next, dichloromethane (50 ml) was added and the crystals thusprecipitated were dissolved. The solution was washed with an diluteaqueous solution of sodium hydrogencarbonate (100 ml) and then with anaqueous solution of hydrochloric acid (0.5 mol/l). The organic layerthus obtained was concentrated and the residue was dissolved in toluene(45 ml) by heating. Then it was cooled by allowed to stand at roomtemperature for crystallization. The crystals thus precipitated werecollected by filtration and dried under reduced pressure to give 6.90 g(51%) of the title compound as yellow crystals.

¹H-NMR (270 MHz, CDCl₃) δ: 1.32 (d, 3.6 Hz, 3H), 4.24–4.42 (m, 3H),8.22–8.33 (m, 4H)

EXAMPLE 97(3S)-(−)-9,10-Difluoro-3-methyl-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylicacid ethyl ester

To S-(−)-7,8-difluoro-3-methyl-2,3-dihydro-4H-[1,4]benzoxazine (15.8 g)was added diethyl ethoxymethylenemalonate (24.0 g) and the mixture wasstirred under reduced pressure at 130 to 140° C. for 1 hour. Aftercooling, the liquid reaction mixture was dissolved in acetic anhydride(50 ml). Under ice-cooling and stirring, a liquid mixture (80 ml) ofacetic anhydride-concentrated sulfuric acid (2:1, V/V) was added inportions thereto. After stirring at room temperature for 1 hour, it wasstirred at a bath temperature of 50 to 60° C. for 30 minutes. Afteradding ice water, the liquid reaction mixture was neutralized by addingpowdery potassium carbonate and extracted with chloroform. The extractwas washed successively with a saturated aqueous solution of sodiumhydrogencarbonate and a saturated aqueous solution of sodium chlorideand dried over mirabilite. After evaporating chloroform, diethyl etherwas added to the residue. The crystals were collected by filtration togive 20.0 g of the title compound.

Melting point: 257 to 258° C.

[α]_(D)=−68.1° (c=0.250, acetic acid)

EXAMPLE 98(3S)-(−)-9,10-Difluoro-3-methyl-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylicacid

The ester compound (19.5 g) obtained above was dissolved in acetic acid(150 ml). After adding conc. hydrochloric acid (400 ml), the mixture wasrefluxed for 3 hours. After cooling, the crystals thus precipitated werecollected by filtration and washed successively with water, ethanol anddiethyl ether followed by drying to give 16.2 g of the title carboxylicacid.

Melting point>300° C.

[α]_(D)=−65.6° (c=0.985, DMSO)

EXAMPLE 99(3S)-(−)-9-Fluoro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylicacid (levofloxacin)

The carboxylic acid (14.3 g) obtained above was suspended in diethylether (600 ml). After adding boron trifluoride diethyl ether complex (70ml), the mixture was stirred at room temperature for 5 hours. Afterdiscarding the supernatant by decantation, the residue was collected byfiltration by adding diethyl ether and washed with diethyl etherfollowed by drying. Then it was dissolved in dimethyl sulfoxide (100ml). After adding triethylamine (14.2 ml) and N-methylpiperazine (7.3ml), the mixture was stirred at room temperature for 18 hours. Afterevaporating the solvent under reduced pressure, diethyl ether was addedto the residue. The yellow powder thus collected by filtration wassuspended in 95% methanol (400 ml) and triethylamine (25 ml) was addedthereto. After heating under reflux for 25 hours, the solvent wasevaporated under reduced pressure. The residue was dissolved in 10%hydrochloric acid (500 ml), washed with chloroform thrice and thenadjusted to pH 11 with an aqueous solution of sodium hydroxide (4mol/l). Next, it was adjusted again to pH 7.3 with hydrochloric acid (1mol/l), extracted with chloroform (2000 ml×3) and dried over mirabilite.After evaporating the chloroform, the crystalline solid thus obtainedwas recrystallized from ethanol-diethyl ether to thereby give 12.0 g ofthe title compound (levofloxacin).

Melting point: 226 to 230° C. (decomposition)

[α]_(D)=−76.9° (c=0.655, NaOH (0.05 mol/l))

EXAMPLE 100(3S)-(−)-9-Fluoro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylicacid (levofloxacin)

(S)-(−)-9,10-Difluoro-3-methyl-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylicacid (281 mg) was dissolved in diethyl ether (30 ml). Under stirring atroom temperature, boron trifluoride diethyl ether complex in largeexcess was added thereto and the mixture was reacted for 45 minutes. Theprecipitate was collected by filtration, washed with diethyl ether anddried under reduced pressure to thereby give a boron chelate compound.

Decomposition point>300° C.

[α]_(D)=−9.4° (c=0.490, DMSO)

Elemental analysis as C₁₃H₈BF₄NO₄

Calculated (%): C, 47.46; H, 2.46; N, 4.26. Found (%) C, 47.68; H, 2.59;N, 4.32.

This chelate compound (310 mg) was dissolved in dimethyl sulfoxide (6ml) and triethylamine (0.32 ml) and N-methylpiperazine (0.13 ml) wereadded thereto. The resultant mixture was stirred at room temperature for17 hours and then solidified to dryness under reduced pressure. Theresidue was washed with diethyl ether and dissolved in 95% ethanol (20ml) containing triethylamine (0.5 ml) followed by heating under refluxfor 8 hours. After cooling, the residue obtained by solidifying todryness was dissolved in dilute hydrochloric acid (5%) and separated byshaking together with chloroform. The aqueous layer was adjusted to pH11 with sodium hydroxide (1 mol/l) and then to pH 7.4 with hydrochloricacid (1 mol/l). Then it was extracted with chloroform (50 ml×3) anddried over mirabilite. After evaporating chloroform, the powder thusobtained was recrystallized from ethanol-diethyl ether to thereby give120 mg of the title compound as transparent fine needles.

Melting point: 225 to 227° C. (decomposition)

Elemental analysis as C₁H₂₀FN₃O₄

Calculated (%): C, 58.37; H, 5.72; N, 11.35. Found (%): C, 58.17; H,5.58; N, 11.27.

EXAMPLE 101(3S)-9,10-Difluoro-3-methyl-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylicacid boron difluoride chelate complex

(S)-Diethyl(7,8-difluoro-3-methyl-3,4-dihydro-2H-[1,4]benzoxazin-4-yl)methylenemalonate(2 g) was mixed with acetic anhydride (2 ml). At 140° C., 47% borontrifluoride/tetrahydrofruan complex (0.8 ml) was added thereto and theresultant mixture was stirred under heating at the same temperature for1 hour. After evaporating the low-boiling matters thus formed, theliquid reaction mixture was cooled to room temperature. After addingacetone (10 ml), the liquid reaction mixture was stirred at the sametemperature for 30 minutes. The crystals thus precipitated werecollected and washed with acetone to give 1.55 g of the title compound.

EXAMPLE 102(3S)-(−)-9-Fluoro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylicacid (levofloxacin)

(S)-(−)-9,10-Difluoro-3-methyl-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylicacid (21 mg) and N-methylpiperazine (30 mg) were dissolved in anhydrousdimethyl sulfoxide (3 ml) and stirred at 130 to 140° C. for 1 hour.After evaporating the solvent, ethanol (2 ml) was added to the residue.The solid thus precipitated was collected by filtration and washedsuccessively with a small amount of ethanol and ether. 14 mg of theobtained powder was subjected to silica gel column chromatography withthe use of 5 g of silica gel and eluted with a lower layer solution ofchloroform-methanol-water (7:3:1) to thereby give(S)-(−)-9-fluoro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylicacid. The above-described filtration mother liquor was fractioned andsubjected to thin layer chromatography (silica gel, 20×20 cm, 0.5 mm),thereby purifying by developing with a lower layer solution ofchloroform-methanol-water (15:3:1). The products were combined tothereby give 14 mg of crystals of the target compound. Melting point:220 to 228° C. (decomposition).

Elemental analysis as C₁₈H₂₀FN₃O₄

Calculated (%): C, 59.82; H, 5.58; N, 11.63. Found (%): C, 60.01; H,5.69; N, 11.53.

MS (m/e); 361 (M⁺)

¹H-NMR (CDCl₃) δ (ppm): 1.63 (3H, d, J=7 Hz), 2.38 (3H, s), 2.54–2.60(4H, m), 3.40–3.44 (4H, m), 4.35–4.52 (3H, m), 7.76 (1H, d), 8.64 (1H,s)

1. A process for producing a compound represented by the formula (VI-a):

which comprises reacting a compound represented by formula (III-1-a):

or a compound represented by the following formula

with a metal borohydride compound in an aprotic solvent in the presenceof an alcohol to give a compound represented by formula (IV-a):

reacting this compound with a compound represented by the followingformula under basic conditions:

to give a compound represented by formula (V-a):

and then treating this compound under basic conditions; wherein, in theabove formulae, X¹, X² and X³ each independently represents a halogenatom; R³ represents a hydrogen atom or a carboxyl-protective group; R⁵and R⁶ each independently represents an alkyl group having 1 to 6 carbonatoms; R⁷ represents a carboxyl-protective group; and Y represents analkoxy group having 1 to 6 carbon atoms, a halogen atom or adialkylamino group (wherein the alkyl groups may be the same ordifferent and each represents an alkyl group having 1 to 6 carbonatoms).
 2. A process for producing a compound represented by formula(VI-a):

which comprises reacting a compound represented by formula (V-a) underbasic conditions:

wherein, in the above formulae, X¹, X² and X³ each independentlyrepresents a halogen atom; and R⁵ and R⁶ each independently representsan alkyl group having from 1 to 6 carbon atoms.
 3. The process asclaimed in claim 2, wherein the basic conditions are basic conditions inwhich a base exists together with a phase transfer catalyst.
 4. Theprocess as claimed in claim 3, wherein the base is an alkali metalhydroxide or an alkaline earth metal hydroxide.
 5. The process asclaimed in claim 3, wherein the base is potassium hydroxide.
 6. Theprocess as claimed in claim 3, wherein the phase transfer catalyst is aquaternary ammonium salt or a crown ether.
 7. The process as claimed inclaim 6, wherein the phase transfer catalyst is a quaternary ammoniumsalt.
 8. The process as claimed in claim 7, wherein the quaternaryammonium salt is selected from the group consisting of tetra(normal-hexyl) ammonium chloride, trimethylbenzylammonium chloride,triethylbenzylammonium chloride, trimethylphenylammonium chloride andtetrabutylammonium hydrogen sulfate.